diff --git a/license-report.md b/license-report.md
index 1e5d2392a5..74193d05bb 100644
--- a/license-report.md
+++ b/license-report.md
@@ -1,6 +1,6 @@
 
     
-# Dependencies of `io.spine:spine-base:1.5.4`
+# Dependencies of `io.spine:spine-base:1.5.5`
 
 ## Runtime
 1. **Group:** com.google.code.findbugs **Name:** jsr305 **Version:** 3.0.2
@@ -330,12 +330,12 @@
  The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
 
-This report was generated on **Mon Apr 06 12:01:12 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Wed Apr 08 17:20:53 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
     
-# Dependencies of `io.spine.tools:spine-errorprone-checks:1.5.4`
+# Dependencies of `io.spine.tools:spine-errorprone-checks:1.5.5`
 
 ## Runtime
 1. **Group:** com.github.ben-manes.caffeine **Name:** caffeine **Version:** 2.7.0
@@ -777,12 +777,12 @@ This report was generated on **Mon Apr 06 12:01:12 EEST 2020** using [Gradle-Lic
  The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
 
-This report was generated on **Mon Apr 06 12:01:13 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Wed Apr 08 17:20:54 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
     
-# Dependencies of `io.spine.tools:spine-javadoc-filter:1.5.4`
+# Dependencies of `io.spine.tools:spine-javadoc-filter:1.5.5`
 
 ## Runtime
 1. **Group:** com.google.android **Name:** annotations **Version:** 4.1.1.4
@@ -1170,12 +1170,12 @@ This report was generated on **Mon Apr 06 12:01:13 EEST 2020** using [Gradle-Lic
  The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
 
-This report was generated on **Mon Apr 06 12:01:14 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Wed Apr 08 17:20:55 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
     
-# Dependencies of `io.spine.tools:spine-javadoc-prettifier:1.5.4`
+# Dependencies of `io.spine.tools:spine-javadoc-prettifier:1.5.5`
 
 ## Runtime
 1. **Group:** com.google.code.findbugs **Name:** jsr305 **Version:** 3.0.2
@@ -1537,12 +1537,12 @@ This report was generated on **Mon Apr 06 12:01:14 EEST 2020** using [Gradle-Lic
  The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
 
-This report was generated on **Mon Apr 06 12:01:14 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Wed Apr 08 17:20:55 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
     
-# Dependencies of `io.spine.tools:spine-model-compiler:1.5.4`
+# Dependencies of `io.spine.tools:spine-model-compiler:1.5.5`
 
 ## Runtime
 1. **Group:** com.google.code.findbugs **Name:** jsr305 **Version:** 3.0.2
@@ -1920,12 +1920,12 @@ This report was generated on **Mon Apr 06 12:01:14 EEST 2020** using [Gradle-Lic
  The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
 
-This report was generated on **Mon Apr 06 12:01:15 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Wed Apr 08 17:20:56 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
     
-# Dependencies of `io.spine.tools:spine-mute-logging:1.5.4`
+# Dependencies of `io.spine.tools:spine-mute-logging:1.5.5`
 
 ## Runtime
 1. **Group:** com.google.auto.value **Name:** auto-value-annotations **Version:** 1.6.3
@@ -2305,12 +2305,12 @@ This report was generated on **Mon Apr 06 12:01:15 EEST 2020** using [Gradle-Lic
  The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
 
-This report was generated on **Mon Apr 06 12:01:15 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Wed Apr 08 17:20:57 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
     
-# Dependencies of `io.spine.tools:spine-plugin-base:1.5.4`
+# Dependencies of `io.spine.tools:spine-plugin-base:1.5.5`
 
 ## Runtime
 1. **Group:** com.google.code.findbugs **Name:** jsr305 **Version:** 3.0.2
@@ -2672,12 +2672,12 @@ This report was generated on **Mon Apr 06 12:01:15 EEST 2020** using [Gradle-Lic
  The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
 
-This report was generated on **Mon Apr 06 12:01:16 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Wed Apr 08 17:20:58 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
     
-# Dependencies of `io.spine.tools:spine-plugin-testlib:1.5.4`
+# Dependencies of `io.spine.tools:spine-plugin-testlib:1.5.5`
 
 ## Runtime
 1. **Group:** com.google.auto.value **Name:** auto-value-annotations **Version:** 1.6.3
@@ -3097,12 +3097,12 @@ This report was generated on **Mon Apr 06 12:01:16 EEST 2020** using [Gradle-Lic
  The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
 
-This report was generated on **Mon Apr 06 12:01:16 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Wed Apr 08 17:20:58 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
     
-# Dependencies of `io.spine.tools:spine-proto-dart-plugin:1.5.4`
+# Dependencies of `io.spine.tools:spine-proto-dart-plugin:1.5.5`
 
 ## Runtime
 1. **Group:** com.google.code.findbugs **Name:** jsr305 **Version:** 3.0.2
@@ -3464,12 +3464,12 @@ This report was generated on **Mon Apr 06 12:01:16 EEST 2020** using [Gradle-Lic
  The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
 
-This report was generated on **Mon Apr 06 12:01:17 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Wed Apr 08 17:20:59 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
     
-# Dependencies of `io.spine.tools:spine-proto-js-plugin:1.5.4`
+# Dependencies of `io.spine.tools:spine-proto-js-plugin:1.5.5`
 
 ## Runtime
 1. **Group:** com.google.code.findbugs **Name:** jsr305 **Version:** 3.0.2
@@ -3831,12 +3831,12 @@ This report was generated on **Mon Apr 06 12:01:17 EEST 2020** using [Gradle-Lic
  The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
 
-This report was generated on **Mon Apr 06 12:01:17 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Wed Apr 08 17:21:00 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
     
-# Dependencies of `io.spine.tools:spine-protoc-api:1.5.4`
+# Dependencies of `io.spine.tools:spine-protoc-api:1.5.5`
 
 ## Runtime
 1. **Group:** com.google.code.findbugs **Name:** jsr305 **Version:** 3.0.2
@@ -4158,12 +4158,12 @@ This report was generated on **Mon Apr 06 12:01:17 EEST 2020** using [Gradle-Lic
  The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
 
-This report was generated on **Mon Apr 06 12:01:18 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Wed Apr 08 17:21:00 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
     
-# Dependencies of `io.spine.tools:spine-protoc-plugin:1.5.4`
+# Dependencies of `io.spine.tools:spine-protoc-plugin:1.5.5`
 
 ## Runtime
 1. **Group:** com.google.code.findbugs **Name:** jsr305 **Version:** 3.0.2
@@ -4493,12 +4493,12 @@ This report was generated on **Mon Apr 06 12:01:18 EEST 2020** using [Gradle-Lic
  The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
 
-This report was generated on **Mon Apr 06 12:01:18 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Wed Apr 08 17:21:01 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
     
-# Dependencies of `io.spine:spine-testlib:1.5.4`
+# Dependencies of `io.spine:spine-testlib:1.5.5`
 
 ## Runtime
 1. **Group:** com.google.auto.value **Name:** auto-value-annotations **Version:** 1.6.3
@@ -4878,12 +4878,12 @@ This report was generated on **Mon Apr 06 12:01:18 EEST 2020** using [Gradle-Lic
  The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
 
-This report was generated on **Mon Apr 06 12:01:18 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Wed Apr 08 17:21:01 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
     
-# Dependencies of `io.spine.tools:spine-tool-base:1.5.4`
+# Dependencies of `io.spine.tools:spine-tool-base:1.5.5`
 
 ## Runtime
 1. **Group:** com.google.code.findbugs **Name:** jsr305 **Version:** 3.0.2
@@ -5213,12 +5213,12 @@ This report was generated on **Mon Apr 06 12:01:18 EEST 2020** using [Gradle-Lic
  The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
 
-This report was generated on **Mon Apr 06 12:01:19 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
+This report was generated on **Wed Apr 08 17:21:02 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
 
 
 
     
-# Dependencies of `io.spine.tools:spine-validation-generator:1.5.4`
+# Dependencies of `io.spine.tools:spine-validation-generator:1.5.5`
 
 ## Runtime
 1. **Group:** com.google.code.findbugs **Name:** jsr305 **Version:** 3.0.2
@@ -5548,4 +5548,4 @@ This report was generated on **Mon Apr 06 12:01:19 EEST 2020** using [Gradle-Lic
  The dependencies distributed under several licenses, are used according their commercial-use-friendly license.
 
 
-This report was generated on **Mon Apr 06 12:01:19 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
\ No newline at end of file
+This report was generated on **Wed Apr 08 17:21:02 EEST 2020** using [Gradle-License-Report plugin](https://github.com/jk1/Gradle-License-Report) by Evgeny Naumenko, licensed under [Apache 2.0 License](https://github.com/jk1/Gradle-License-Report/blob/master/LICENSE).
\ No newline at end of file
diff --git a/pom.xml b/pom.xml
index a53084ee50..506ec3a047 100644
--- a/pom.xml
+++ b/pom.xml
@@ -12,7 +12,7 @@ all modules and does not describe the project structure per-subproject.
 
 <groupId>io.spine</groupId>
 <artifactId>spine-base</artifactId>
-<version>1.5.4</version>
+<version>1.5.5</version>
 
 <inceptionYear>2015</inceptionYear>
 
@@ -154,7 +154,7 @@ all modules and does not describe the project structure per-subproject.
   <dependency>
     <groupId>io.spine.tools</groupId>
     <artifactId>spine-protoc-plugin</artifactId>
-    <version>1.5.4</version>
+    <version>1.5.5</version>
     <scope>test</scope>
   </dependency>
   <dependency>
diff --git a/tools/proto-js-plugin/src/main/java/io/spine/js/generate/resolve/DirectoryPattern.java b/tools/plugin-base/src/main/java/io/spine/tools/code/structure/DirectoryPattern.java
similarity index 96%
rename from tools/proto-js-plugin/src/main/java/io/spine/js/generate/resolve/DirectoryPattern.java
rename to tools/plugin-base/src/main/java/io/spine/tools/code/structure/DirectoryPattern.java
index cbd124ae28..7843c56ce7 100644
--- a/tools/proto-js-plugin/src/main/java/io/spine/js/generate/resolve/DirectoryPattern.java
+++ b/tools/plugin-base/src/main/java/io/spine/tools/code/structure/DirectoryPattern.java
@@ -18,12 +18,12 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.js.generate.resolve;
+package io.spine.tools.code.structure;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Joiner;
-import io.spine.code.fs.js.DirectoryReference;
-import io.spine.code.fs.js.FileReference;
+import io.spine.code.fs.DirectoryReference;
+import io.spine.code.fs.FileReference;
 
 import java.util.List;
 import java.util.Objects;
@@ -62,7 +62,6 @@ private DirectoryPattern(DirectoryReference directory, boolean includeNested) {
      *         the value of the pattern
      * @return a new instance
      */
-    @SuppressWarnings("ResultOfMethodCallIgnored" /* The result can be ignored. */)
     public static DirectoryPattern of(String value) {
         checkNotEmptyOrBlank(value);
         boolean includeNested = value.endsWith(INCLUDE_NESTED_PATTERN_ENDING);
diff --git a/tools/proto-js-plugin/src/main/java/io/spine/js/generate/resolve/ExternalModule.java b/tools/plugin-base/src/main/java/io/spine/tools/code/structure/ExternalModule.java
similarity index 87%
rename from tools/proto-js-plugin/src/main/java/io/spine/js/generate/resolve/ExternalModule.java
rename to tools/plugin-base/src/main/java/io/spine/tools/code/structure/ExternalModule.java
index 40e1e94535..2ff2325d03 100644
--- a/tools/proto-js-plugin/src/main/java/io/spine/js/generate/resolve/ExternalModule.java
+++ b/tools/plugin-base/src/main/java/io/spine/tools/code/structure/ExternalModule.java
@@ -18,12 +18,13 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.js.generate.resolve;
+package io.spine.tools.code.structure;
 
 import com.google.common.base.Joiner;
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
-import io.spine.code.fs.js.DirectoryReference;
-import io.spine.code.fs.js.FileReference;
+import io.spine.code.fs.DirectoryReference;
+import io.spine.code.fs.FileReference;
 
 import java.util.Collection;
 import java.util.Objects;
@@ -34,9 +35,9 @@
 import static io.spine.util.Preconditions2.checkNotEmptyOrBlank;
 
 /**
- * An external JavaScript module used in a project.
+ * An external library module used in a project.
  *
- * <p>External means that it is provided by an artifact repository like NPM.
+ * <p>An external module is typically provided by a package manager, such as NPM or Pub.
  */
 public final class ExternalModule {
 
@@ -65,7 +66,7 @@ public ExternalModule(String name, Collection<DirectoryPattern> directories) {
      * @throws IllegalStateException
      *         if the file is not provided by the module
      */
-    FileReference fileInModule(FileReference fileReference) {
+    public FileReference fileInModule(FileReference fileReference) {
         Optional<DirectoryPattern> matchingDirectory = matchingDirectory(fileReference);
         checkState(matchingDirectory.isPresent());
         DirectoryReference directory = matchingDirectory.get()
@@ -83,11 +84,18 @@ FileReference fileInModule(FileReference fileReference) {
      *         the file to check
      * @return {@code true} if the module provides the file
      */
-    boolean provides(FileReference fileReference) {
+    public boolean provides(FileReference fileReference) {
         boolean result = matchingDirectory(fileReference).isPresent();
         return result;
     }
 
+    /**
+     * Obtains the name of the module.
+     */
+    public String name() {
+        return name;
+    }
+
     private Optional<DirectoryPattern> matchingDirectory(FileReference fileReference) {
         DirectoryReference directory = fileReference.directory();
         for (DirectoryPattern pattern : directories) {
@@ -133,6 +141,13 @@ public static ExternalModule spineUsers() {
         return new ExternalModule("spine-users", directories);
     }
 
+    /**
+     * All the modules in {@link #spineWeb()} and {@link #spineUsers()}.
+     */
+    public static ImmutableList<ExternalModule> predefinedModules() {
+        return ImmutableList.of(spineWeb(), spineUsers());
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) {
diff --git a/tools/proto-js-plugin/src/main/java/io/spine/js/generate/resolve/package-info.java b/tools/plugin-base/src/main/java/io/spine/tools/code/structure/package-info.java
similarity index 92%
rename from tools/proto-js-plugin/src/main/java/io/spine/js/generate/resolve/package-info.java
rename to tools/plugin-base/src/main/java/io/spine/tools/code/structure/package-info.java
index 5810177a3d..e54cbf6162 100644
--- a/tools/proto-js-plugin/src/main/java/io/spine/js/generate/resolve/package-info.java
+++ b/tools/plugin-base/src/main/java/io/spine/tools/code/structure/package-info.java
@@ -19,11 +19,11 @@
  */
 
 /**
- * The classes which resolve imports in generated code.
+ * Classes which work with source code directory structure.
  */
 @CheckReturnValue
 @ParametersAreNonnullByDefault
-package io.spine.js.generate.resolve;
+package io.spine.tools.code.structure;
 
 import javax.annotation.CheckReturnValue;
 import javax.annotation.ParametersAreNonnullByDefault;
diff --git a/tools/plugin-base/src/main/java/io/spine/tools/gradle/GradleTask.java b/tools/plugin-base/src/main/java/io/spine/tools/gradle/GradleTask.java
index 077f525b82..8c9a48da9a 100644
--- a/tools/plugin-base/src/main/java/io/spine/tools/gradle/GradleTask.java
+++ b/tools/plugin-base/src/main/java/io/spine/tools/gradle/GradleTask.java
@@ -296,7 +296,7 @@ private void dependTask(Task task, Project project) {
             }
             if (followingTask != null) {
                 TaskContainer existingTasks = project.getTasks();
-                existingTasks.getByPath(followingTask.name())
+                existingTasks.getByName(followingTask.name())
                              .dependsOn(task);
             }
             if (previousTaskOfAllProjects != null) {
diff --git a/tools/plugin-base/src/main/java/io/spine/tools/gradle/ProtoDartTaskName.java b/tools/plugin-base/src/main/java/io/spine/tools/gradle/ProtoDartTaskName.java
index 4a70a34aa4..c63d29f5d3 100644
--- a/tools/plugin-base/src/main/java/io/spine/tools/gradle/ProtoDartTaskName.java
+++ b/tools/plugin-base/src/main/java/io/spine/tools/gradle/ProtoDartTaskName.java
@@ -58,5 +58,10 @@ public enum ProtoDartTaskName implements TaskName {
      *
      * <p>Works only with the {@code test} scope files.
      */
-    copyTestGeneratedDart
+    copyTestGeneratedDart,
+
+    /**
+     * Rewrites the Dart source files generated from Protobuf with the resolved absolute imports.
+     */
+    resolveImports
 }
diff --git a/tools/proto-js-plugin/src/test/java/io/spine/js/generate/resolve/DirectoryPatternTest.java b/tools/plugin-base/src/test/java/io/spine/tools/code/structure/DirectoryPatternTest.java
similarity index 98%
rename from tools/proto-js-plugin/src/test/java/io/spine/js/generate/resolve/DirectoryPatternTest.java
rename to tools/plugin-base/src/test/java/io/spine/tools/code/structure/DirectoryPatternTest.java
index e2ce73c3f5..32ac8328b0 100644
--- a/tools/proto-js-plugin/src/test/java/io/spine/js/generate/resolve/DirectoryPatternTest.java
+++ b/tools/plugin-base/src/test/java/io/spine/tools/code/structure/DirectoryPatternTest.java
@@ -18,11 +18,11 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.js.generate.resolve;
+package io.spine.tools.code.structure;
 
 import com.google.common.testing.EqualsTester;
 import com.google.common.testing.NullPointerTester;
-import io.spine.code.fs.js.DirectoryReference;
+import io.spine.code.fs.DirectoryReference;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 
diff --git a/tools/proto-js-plugin/src/test/java/io/spine/js/generate/resolve/ExternalModuleTest.java b/tools/plugin-base/src/test/java/io/spine/tools/code/structure/ExternalModuleTest.java
similarity index 90%
rename from tools/proto-js-plugin/src/test/java/io/spine/js/generate/resolve/ExternalModuleTest.java
rename to tools/plugin-base/src/test/java/io/spine/tools/code/structure/ExternalModuleTest.java
index ccacea3996..8320a32329 100644
--- a/tools/proto-js-plugin/src/test/java/io/spine/js/generate/resolve/ExternalModuleTest.java
+++ b/tools/plugin-base/src/test/java/io/spine/tools/code/structure/ExternalModuleTest.java
@@ -18,15 +18,17 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.js.generate.resolve;
+package io.spine.tools.code.structure;
 
 import com.google.common.testing.EqualsTester;
-import io.spine.code.fs.js.FileReference;
+import io.spine.code.fs.FileReference;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 
-import static io.spine.js.generate.resolve.given.Given.newModule;
+import java.util.List;
+
 import static java.util.Collections.emptySet;
+import static java.util.Collections.singletonList;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
@@ -104,4 +106,10 @@ void acceptOnlyProvidedProto() {
                 () -> module.fileInModule(reference)
         );
     }
+
+    private static ExternalModule newModule(String moduleName, String directoryPattern) {
+        DirectoryPattern pattern = DirectoryPattern.of(directoryPattern);
+        List<DirectoryPattern> patterns = singletonList(pattern);
+        return new ExternalModule(moduleName, patterns);
+    }
 }
diff --git a/tools/proto-dart-plugin/src/main/java/io/spine/generate/dart/Extension.java b/tools/proto-dart-plugin/src/main/java/io/spine/generate/dart/Extension.java
index 146695c1ca..74d8cf818f 100644
--- a/tools/proto-dart-plugin/src/main/java/io/spine/generate/dart/Extension.java
+++ b/tools/proto-dart-plugin/src/main/java/io/spine/generate/dart/Extension.java
@@ -20,7 +20,10 @@
 
 package io.spine.generate.dart;
 
+import com.google.common.collect.ImmutableList;
 import io.spine.code.fs.dart.DefaultDartProject;
+import io.spine.tools.code.structure.DirectoryPattern;
+import io.spine.tools.code.structure.ExternalModule;
 import io.spine.tools.gradle.GradleExtension;
 import org.gradle.api.Project;
 import org.gradle.api.file.DirectoryProperty;
@@ -29,6 +32,12 @@
 
 import java.io.File;
 import java.nio.file.Path;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+
+import static com.google.common.collect.Maps.newHashMap;
+import static java.util.stream.Collectors.toList;
 
 /**
  * DSL extension for configuring Protobuf-to-Dart compilation.
@@ -50,6 +59,39 @@ public final class Extension extends GradleExtension {
     private final DirectoryProperty testDir;
     private final DirectoryProperty mainGeneratedDir;
     private final DirectoryProperty testGeneratedDir;
+
+    /**
+     * Names of Dart modules and directories they provide.
+     *
+     * <p>Information about modules is used to resolve imports in generated Protobuf files.
+     *
+     * <p>Import resolution only applies to Dart files generated from Protobuf. Such files must
+     * have one of extensions: {@code .pb.dart}, {@code .pbenum.dart}, {@code .pbserver.dart}, or
+     * {@code .pbjson.dart}. All other files are ignored.
+     *
+     * <p>An example of the definition:
+     * <pre>{@code
+     * modules = [
+     *      // The module provides `company/client` directory (not including subdirectories).
+     *      // So, an import path like {@code ../company/client/file.pb.dart}
+     *      // becomes {@code package:client/company/client/file.pb.dart}.
+     *      'client' : ['company/client'],
+     *
+     *      // The module provides `company/server` directory (including subdirectories).
+     *      // So, an import path like {@code ../company/server/nested/file.pb.dart}
+     *      // becomes {@code package:server/company/server/nested/file.pb.dart}.
+     *      'server' : ['company/server/*'],
+     *
+     *      // The module provides 'proto/company` directory.
+     *      // So, an import pah like {@code ../company/file.pbenum.dart}
+     *      // becomes {@code package:common_types/proto/company/file.pbenum.dart}.
+     *      'common_types' : ['proto/company']
+     * ]
+     * }</pre>
+     */
+    @SuppressWarnings("PublicField" /* Expose fields as a Gradle extension */)
+    public Map<String, List<String>> modules = newHashMap();
+
     private final Project project;
 
     Extension(Project project) {
@@ -225,6 +267,16 @@ Path testGeneratedDir() {
                                     .toPath();
     }
 
+    ImmutableList<ExternalModule> modules() {
+        ImmutableList.Builder<ExternalModule> modules = ImmutableList.builder();
+        for (String moduleName : this.modules.keySet()) {
+            List<DirectoryPattern> patterns = patterns(this.modules.get(moduleName));
+            ExternalModule module = new ExternalModule(moduleName, patterns);
+            modules.add(module);
+        }
+        return modules.build();
+    }
+
     /**
      * Finalizes all configurable values.
      *
@@ -245,6 +297,12 @@ private File file(Property<Object> property) {
         return project.file(property.get());
     }
 
+    private static List<DirectoryPattern> patterns(Collection<String> rawPatterns) {
+        return rawPatterns.stream()
+                          .map(DirectoryPattern::of)
+                          .collect(toList());
+    }
+
     @Override
     protected DefaultDartProject defaultProject(Project project) {
         return DefaultDartProject.at(project.getProjectDir().toPath());
diff --git a/tools/proto-dart-plugin/src/main/java/io/spine/generate/dart/ProtoDartPlugin.java b/tools/proto-dart-plugin/src/main/java/io/spine/generate/dart/ProtoDartPlugin.java
index 39e6f6d85f..31441f9884 100644
--- a/tools/proto-dart-plugin/src/main/java/io/spine/generate/dart/ProtoDartPlugin.java
+++ b/tools/proto-dart-plugin/src/main/java/io/spine/generate/dart/ProtoDartPlugin.java
@@ -28,13 +28,17 @@
 import org.gradle.api.Plugin;
 import org.gradle.api.Project;
 import org.gradle.api.file.DirectoryProperty;
+import org.gradle.api.file.FileTree;
 import org.gradle.api.tasks.Copy;
 
 import java.io.File;
+import java.nio.file.Path;
 
+import static io.spine.generate.dart.SourceFile.isGeneratedDart;
 import static io.spine.tools.gradle.BaseTaskName.assemble;
 import static io.spine.tools.gradle.ProtoDartTaskName.copyGeneratedDart;
 import static io.spine.tools.gradle.ProtoDartTaskName.copyTestGeneratedDart;
+import static io.spine.tools.gradle.ProtoDartTaskName.resolveImports;
 import static io.spine.tools.gradle.ProtobufTaskName.generateProto;
 import static io.spine.tools.gradle.ProtobufTaskName.generateTestProto;
 import static io.spine.tools.gradle.ProtocPluginName.dart;
@@ -62,6 +66,7 @@ public void apply(Project project) {
 
         createMainCopyTask(project, extension);
         createTestCopyTask(project, extension);
+        createResolveImportTask(project, extension);
     }
 
     private static void createMainCopyTask(Project project, Extension extension) {
@@ -94,4 +99,30 @@ private static void createCopyTask(Project project, Extension extension, SourceS
                .getByName(assemble.name())
                .dependsOn(taskName.name());
     }
+
+    private void createResolveImportTask(Project project, Extension extension) {
+        newTask(resolveImports, task -> {
+            FileTree generatedDir = extension.getMainGeneratedDir()
+                                             .getAsFileTree();
+            generatedDir.forEach(file -> resolveImports(file, extension));
+        })
+                .insertAfterTask(copyGeneratedDart)
+                .insertBeforeTask(assemble)
+                .applyNowTo(project);
+    }
+
+    private void resolveImports(File sourceFile, Extension extension) {
+        Path asPath = sourceFile.toPath();
+        if (!isGeneratedDart(asPath)) {
+            return;
+        }
+        _debug().log("Resolving imports in file %s", sourceFile);
+        SourceFile file = SourceFile.read(sourceFile.toPath());
+        Path libPath = extension.getLibDir()
+                                .getAsFile()
+                                .map(File::toPath)
+                                .get();
+        file.resolveImports(extension.modules(), libPath);
+        file.store();
+    }
 }
diff --git a/tools/proto-dart-plugin/src/main/java/io/spine/generate/dart/SourceFile.java b/tools/proto-dart-plugin/src/main/java/io/spine/generate/dart/SourceFile.java
new file mode 100644
index 0000000000..5480fc3281
--- /dev/null
+++ b/tools/proto-dart-plugin/src/main/java/io/spine/generate/dart/SourceFile.java
@@ -0,0 +1,134 @@
+/*
+ * Copyright 2020, TeamDev. All rights reserved.
+ *
+ * Redistribution and use in source and/or binary forms, with or without
+ * modification, must retain the above copyright notice and the following
+ * disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package io.spine.generate.dart;
+
+import com.google.common.collect.ImmutableList;
+import io.spine.code.AbstractSourceFile;
+import io.spine.code.fs.FileReference;
+import io.spine.logging.Logging;
+import io.spine.tools.code.structure.ExternalModule;
+import org.checkerframework.checker.regex.qual.Regex;
+import org.gradle.api.GradleException;
+
+import java.io.IOException;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+import static java.lang.String.format;
+import static java.nio.file.Files.isRegularFile;
+import static java.nio.file.Files.readAllLines;
+import static java.nio.file.Files.write;
+import static java.util.regex.Pattern.compile;
+
+/**
+ * A Dart source file.
+ */
+final class SourceFile extends AbstractSourceFile implements Logging {
+
+    @Regex(2)
+    private static final Pattern IMPORT_PATTERN = compile("import [\"']([^:]+)[\"'] as (.+);");
+
+    private List<String> lines;
+
+    private SourceFile(Path path, List<String> lines) {
+        super(path);
+        this.lines = lines;
+    }
+
+    /**
+     * Reads the file from the local file system.
+     */
+    static SourceFile read(Path path) {
+        checkNotNull(path);
+        try {
+            List<String> lines = readAllLines(path);
+            return new SourceFile(path, lines);
+        } catch (IOException e) {
+            throw new GradleException(format("Unable to read file `%s`.", path), e);
+        }
+    }
+
+    static boolean isGeneratedDart(Path file) {
+        if (!isRegularFile(file)) {
+            return false;
+        }
+        return file.endsWith(".pb.dart")
+                || file.endsWith(".pbenum.dart")
+                || file.endsWith(".pbserver.dart")
+                || file.endsWith(".pbjson.dart");
+    }
+
+    /**
+     * Resolves the relative imports in the file into absolute ones with the given modules.
+     */
+    void resolveImports(ImmutableList<ExternalModule> modules, Path libPath) {
+        List<String> processedLines = new ArrayList<>();
+        for (String line : lines) {
+            String processedLine = resolveImportInLine(line, modules, libPath);
+            processedLines.add(processedLine);
+        }
+        lines = processedLines;
+    }
+
+    private String resolveImportInLine(String line,
+                                       ImmutableList<ExternalModule> modules,
+                                       Path libPath) {
+        Matcher matcher = IMPORT_PATTERN.matcher(line);
+        if (matcher.matches()) {
+            _debug().log("Import found: `%s`", line);
+            String path = matcher.group(1);
+            Path absolutePath = path().getParent()
+                                      .resolve(path)
+                                      .normalize();
+            _debug().log("Resolved against this file: `%s`", absolutePath);
+            Path relativeImport = libPath.relativize(absolutePath);
+            _debug().log("Relative: `%s`", relativeImport);
+            FileReference reference = FileReference.of(relativeImport.toString());
+            for (ExternalModule module : modules) {
+                if (module.provides(reference)) {
+                    String importStatement = format("import 'package:%s/%s' as %s;",
+                                                    module.name(),
+                                                    relativeImport,
+                                                    matcher.group(2));
+                    _debug().log("Replacing with %s", importStatement);
+                    return importStatement;
+                }
+            }
+        }
+        return line;
+    }
+
+    /**
+     * Rewrites this file.
+     */
+    void store() {
+        Path path = path();
+        try {
+            write(path, lines);
+        } catch (IOException e) {
+            throw new GradleException(format("Unable to write file `%s`.", path), e);
+        }
+    }
+}
diff --git a/tools/proto-dart-plugin/src/test/java/io/spine/generate/dart/ProtoDartPluginTest.java b/tools/proto-dart-plugin/src/test/java/io/spine/generate/dart/ProtoDartPluginTest.java
index cb1828358d..ce2a7c2e9e 100644
--- a/tools/proto-dart-plugin/src/test/java/io/spine/generate/dart/ProtoDartPluginTest.java
+++ b/tools/proto-dart-plugin/src/test/java/io/spine/generate/dart/ProtoDartPluginTest.java
@@ -20,6 +20,7 @@
 
 package io.spine.generate.dart;
 
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import io.spine.tools.gradle.TaskName;
 import org.gradle.api.Project;
 import org.gradle.api.Task;
@@ -35,6 +36,7 @@
 import static io.spine.tools.gradle.BaseTaskName.assemble;
 import static io.spine.tools.gradle.ProtoDartTaskName.copyGeneratedDart;
 import static io.spine.tools.gradle.ProtoDartTaskName.copyTestGeneratedDart;
+import static io.spine.tools.gradle.ProtoDartTaskName.resolveImports;
 
 @DisplayName("`ProtoDartPlugin` should")
 class ProtoDartPluginTest {
@@ -57,10 +59,10 @@ void createMainTask() {
         ProtoDartPlugin plugin = new ProtoDartPlugin();
         plugin.apply(project);
 
-        Task task = task(copyGeneratedDart);
+        Task task = findTask(copyGeneratedDart);
         assertThat(task.getDependsOn()).isNotEmpty();
 
-        Task assembleTask = task(assemble);
+        Task assembleTask = findTask(assemble);
         assertThat(assembleTask.getDependsOn()).contains(task.getName());
     }
 
@@ -70,14 +72,24 @@ void createTestTask() {
         ProtoDartPlugin plugin = new ProtoDartPlugin();
         plugin.apply(project);
 
-        Task task = task(copyTestGeneratedDart);
+        Task task = findTask(copyTestGeneratedDart);
         assertThat(task.getDependsOn()).isNotEmpty();
 
-        Task assembleTask = task(assemble);
+        Task assembleTask = findTask(assemble);
         assertThat(assembleTask.getDependsOn()).contains(task.getName());
     }
 
-    private Task task(TaskName name) {
+    @Test
+    @DisplayName("create `resolveImports` task")
+    void createResolveTask() {
+        ProtoDartPlugin plugin = new ProtoDartPlugin();
+        plugin.apply(project);
+
+        findTask(resolveImports);
+    }
+
+    @CanIgnoreReturnValue
+    private Task findTask(TaskName name) {
         Task task = project.getTasks()
                            .findByName(name.name());
         assertThat(task).isNotNull();
diff --git a/tools/proto-js-plugin/src/main/java/io/spine/js/generate/resolve/ImportStatement.java b/tools/proto-js-plugin/src/main/java/io/spine/js/generate/imports/ImportStatement.java
similarity index 92%
rename from tools/proto-js-plugin/src/main/java/io/spine/js/generate/resolve/ImportStatement.java
rename to tools/proto-js-plugin/src/main/java/io/spine/js/generate/imports/ImportStatement.java
index 45026415db..a1e21d768a 100644
--- a/tools/proto-js-plugin/src/main/java/io/spine/js/generate/resolve/ImportStatement.java
+++ b/tools/proto-js-plugin/src/main/java/io/spine/js/generate/imports/ImportStatement.java
@@ -18,9 +18,9 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.js.generate.resolve;
+package io.spine.js.generate.imports;
 
-import io.spine.code.fs.js.FileReference;
+import io.spine.code.fs.FileReference;
 import io.spine.logging.Logging;
 
 import java.io.File;
@@ -66,7 +66,7 @@ static boolean hasImport(String line) {
     /**
      * Obtains the file reference used in this import.
      */
-    FileReference path() {
+    public FileReference path() {
         int beginIndex = text.indexOf(IMPORT_BEGIN_SIGN) + IMPORT_BEGIN_SIGN.length();
         int endIndex = text.indexOf(IMPORT_END_SIGN, beginIndex);
         String importPath = text.substring(beginIndex, endIndex);
@@ -76,7 +76,7 @@ FileReference path() {
     /**
      * Obtains a new instance with the updated path in the import statement.
      */
-    ImportStatement replacePath(CharSequence newPath) {
+    public ImportStatement replacePath(CharSequence newPath) {
         String updatedText = text.replace(path().value(), newPath);
         return new ImportStatement(updatedText, originFile);
     }
@@ -91,7 +91,7 @@ String text() {
     /**
      * Tells whether the imported file is present on a file system.
      */
-    boolean importedFileExists() {
+    public boolean importedFileExists() {
         Path filePath = importedFilePath();
         boolean exists = filePath.toFile()
                                  .exists();
@@ -102,7 +102,7 @@ boolean importedFileExists() {
     /**
      * Obtains the absolute path to the imported file.
      */
-    Path importedFilePath() {
+    public Path importedFilePath() {
         FileReference fileReference = path();
         Path filePath = sourceDirectory().resolve(fileReference.value());
         return filePath.normalize();
@@ -111,7 +111,7 @@ Path importedFilePath() {
     /**
      * Obtains the path of the directory with the file containing this import.
      */
-    Path sourceDirectory() {
+    public Path sourceDirectory() {
         return originFile.getParentFile()
                          .toPath();
     }
diff --git a/tools/proto-js-plugin/src/main/java/io/spine/js/generate/resolve/JsFile.java b/tools/proto-js-plugin/src/main/java/io/spine/js/generate/imports/JsFile.java
similarity index 93%
rename from tools/proto-js-plugin/src/main/java/io/spine/js/generate/resolve/JsFile.java
rename to tools/proto-js-plugin/src/main/java/io/spine/js/generate/imports/JsFile.java
index ca1490c877..20b7fb5f8c 100644
--- a/tools/proto-js-plugin/src/main/java/io/spine/js/generate/resolve/JsFile.java
+++ b/tools/proto-js-plugin/src/main/java/io/spine/js/generate/imports/JsFile.java
@@ -18,7 +18,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.js.generate.resolve;
+package io.spine.js.generate.imports;
 
 import com.google.common.base.Charsets;
 
@@ -39,13 +39,13 @@
 /**
  * A JavaScript file present on a file system.
  */
-final class JsFile {
+public final class JsFile {
 
     private static final String EXTENSION = ".js";
 
     private final Path path;
 
-    JsFile(Path path) {
+    public JsFile(Path path) {
         checkArgument(path.toString()
                           .endsWith(EXTENSION), "A JavaScript file is expected.");
         checkArgument(path.toFile()
@@ -63,7 +63,7 @@ final class JsFile {
      * @param processFunction
      *         the function processing an import
      */
-    void processImports(Predicate<ImportStatement> importFilter,
+    public void processImports(Predicate<ImportStatement> importFilter,
                         ProcessImport processFunction) {
         try (Stream<String> lines = Files.lines(path)) {
             List<String> updatedLines = lines
@@ -101,6 +101,6 @@ private void rewriteFile(Iterable<String> lines) {
     /**
      * A function processing an import statement.
      */
-    interface ProcessImport extends UnaryOperator<ImportStatement> {
+    public interface ProcessImport extends UnaryOperator<ImportStatement> {
     }
 }
diff --git a/tools/proto-js-plugin/src/main/java/io/spine/js/generate/resolve/ResolveImports.java b/tools/proto-js-plugin/src/main/java/io/spine/js/generate/imports/ResolveImports.java
similarity index 98%
rename from tools/proto-js-plugin/src/main/java/io/spine/js/generate/resolve/ResolveImports.java
rename to tools/proto-js-plugin/src/main/java/io/spine/js/generate/imports/ResolveImports.java
index 182e20838e..456a654d9d 100644
--- a/tools/proto-js-plugin/src/main/java/io/spine/js/generate/resolve/ResolveImports.java
+++ b/tools/proto-js-plugin/src/main/java/io/spine/js/generate/imports/ResolveImports.java
@@ -18,19 +18,20 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.js.generate.resolve;
+package io.spine.js.generate.imports;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Predicate;
 import com.google.common.collect.ImmutableSet;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.protobuf.Descriptors.FileDescriptor;
+import io.spine.code.fs.FileReference;
 import io.spine.code.fs.js.Directory;
 import io.spine.code.fs.js.FileName;
-import io.spine.code.fs.js.FileReference;
 import io.spine.code.proto.FileSet;
 import io.spine.js.generate.GenerationTask;
 import io.spine.logging.Logging;
+import io.spine.tools.code.structure.ExternalModule;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.nio.file.Path;
diff --git a/tools/proto-js-plugin/src/main/java/io/spine/js/generate/imports/package-info.java b/tools/proto-js-plugin/src/main/java/io/spine/js/generate/imports/package-info.java
new file mode 100644
index 0000000000..839661a05f
--- /dev/null
+++ b/tools/proto-js-plugin/src/main/java/io/spine/js/generate/imports/package-info.java
@@ -0,0 +1,31 @@
+/*
+ * Copyright 2020, TeamDev. All rights reserved.
+ *
+ * Redistribution and use in source and/or binary forms, with or without
+ * modification, must retain the above copyright notice and the following
+ * disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/**
+ * Classes for resolving JS imports.
+ */
+
+@CheckReturnValue
+@ParametersAreNonnullByDefault
+package io.spine.js.generate.imports;
+
+import com.google.errorprone.annotations.CheckReturnValue;
+
+import javax.annotation.ParametersAreNonnullByDefault;
diff --git a/tools/proto-js-plugin/src/main/java/io/spine/js/gradle/Extension.java b/tools/proto-js-plugin/src/main/java/io/spine/js/gradle/Extension.java
index aaccfd2ff8..6faf287a3f 100644
--- a/tools/proto-js-plugin/src/main/java/io/spine/js/gradle/Extension.java
+++ b/tools/proto-js-plugin/src/main/java/io/spine/js/gradle/Extension.java
@@ -21,12 +21,11 @@
 package io.spine.js.gradle;
 
 import com.google.common.annotations.VisibleForTesting;
-import com.google.common.collect.ImmutableList;
 import io.spine.code.fs.DefaultProject;
 import io.spine.code.fs.js.DefaultJsProject;
 import io.spine.code.fs.js.Directory;
-import io.spine.js.generate.resolve.DirectoryPattern;
-import io.spine.js.generate.resolve.ExternalModule;
+import io.spine.tools.code.structure.DirectoryPattern;
+import io.spine.tools.code.structure.ExternalModule;
 import io.spine.tools.gradle.GradleExtension;
 import org.gradle.api.Project;
 import org.gradle.api.Task;
@@ -43,6 +42,7 @@
 import static com.google.common.collect.Lists.newArrayList;
 import static com.google.common.collect.Maps.newHashMap;
 import static io.spine.js.gradle.ProtoJsPlugin.extensionName;
+import static io.spine.tools.code.structure.ExternalModule.predefinedModules;
 import static java.util.stream.Collectors.toList;
 
 /**
@@ -78,7 +78,7 @@ public class Extension extends GradleExtension {
      * <p>Information about modules is used to resolve imports in generated Protobuf files.
      *
      * <p>Additionally to modules specified via the property,
-     * the {@linkplain #predefinedModules() predefined Spine} modules are used.
+     * the {@linkplain ExternalModule#predefinedModules() predefined Spine} modules are used.
      *
      * <p>An example of the definition:
      * <pre>{@code
@@ -172,17 +172,6 @@ static Extension extension(Project project) {
                        .getByName(extensionName());
     }
 
-    /**
-     * Obtains the external modules published by Spine.
-     */
-    @VisibleForTesting
-    static List<ExternalModule> predefinedModules() {
-        return ImmutableList.of(
-                ExternalModule.spineWeb(),
-                ExternalModule.spineUsers()
-        );
-    }
-
     private static List<DirectoryPattern> patterns(Collection<String> rawPatterns) {
         return rawPatterns.stream()
                           .map(DirectoryPattern::of)
diff --git a/tools/proto-js-plugin/src/main/java/io/spine/js/gradle/ProtoJsPlugin.java b/tools/proto-js-plugin/src/main/java/io/spine/js/gradle/ProtoJsPlugin.java
index 87b75ce3ef..e2f769b688 100644
--- a/tools/proto-js-plugin/src/main/java/io/spine/js/gradle/ProtoJsPlugin.java
+++ b/tools/proto-js-plugin/src/main/java/io/spine/js/gradle/ProtoJsPlugin.java
@@ -26,10 +26,10 @@
 import io.spine.code.proto.FileSet;
 import io.spine.js.generate.AppendTypeUrlGetter;
 import io.spine.js.generate.GenerationTask;
+import io.spine.js.generate.imports.ResolveImports;
 import io.spine.js.generate.index.GenerateIndexFile;
 import io.spine.js.generate.parse.GenerateKnownTypeParsers;
-import io.spine.js.generate.resolve.ExternalModule;
-import io.spine.js.generate.resolve.ResolveImports;
+import io.spine.tools.code.structure.ExternalModule;
 import io.spine.tools.gradle.BaseTaskName;
 import io.spine.tools.gradle.GradleTask;
 import io.spine.tools.gradle.ProtoPlugin;
diff --git a/tools/proto-js-plugin/src/test/java/io/spine/js/generate/resolve/ImportStatementTest.java b/tools/proto-js-plugin/src/test/java/io/spine/js/generate/imports/ImportStatementTest.java
similarity index 92%
rename from tools/proto-js-plugin/src/test/java/io/spine/js/generate/resolve/ImportStatementTest.java
rename to tools/proto-js-plugin/src/test/java/io/spine/js/generate/imports/ImportStatementTest.java
index 08146d49c7..1c3ec044d9 100644
--- a/tools/proto-js-plugin/src/test/java/io/spine/js/generate/resolve/ImportStatementTest.java
+++ b/tools/proto-js-plugin/src/test/java/io/spine/js/generate/imports/ImportStatementTest.java
@@ -18,9 +18,9 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.js.generate.resolve;
+package io.spine.js.generate.imports;
 
-import io.spine.code.fs.js.FileReference;
+import io.spine.code.fs.FileReference;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 
@@ -29,8 +29,8 @@
 import java.nio.file.Paths;
 
 import static com.google.common.truth.Truth.assertThat;
-import static io.spine.js.generate.resolve.given.Given.importWithPath;
-import static io.spine.js.generate.resolve.given.Given.relativeImportPath;
+import static io.spine.js.generate.imports.given.Given.importWithPath;
+import static io.spine.js.generate.imports.given.Given.relativeImportPath;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
 @DisplayName("ImportStatement should")
diff --git a/tools/proto-js-plugin/src/test/java/io/spine/js/generate/resolve/JsFileTest.java b/tools/proto-js-plugin/src/test/java/io/spine/js/generate/imports/JsFileTest.java
similarity index 97%
rename from tools/proto-js-plugin/src/test/java/io/spine/js/generate/resolve/JsFileTest.java
rename to tools/proto-js-plugin/src/test/java/io/spine/js/generate/imports/JsFileTest.java
index a2fab1eb48..738cc77346 100644
--- a/tools/proto-js-plugin/src/test/java/io/spine/js/generate/resolve/JsFileTest.java
+++ b/tools/proto-js-plugin/src/test/java/io/spine/js/generate/imports/JsFileTest.java
@@ -18,7 +18,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.js.generate.resolve;
+package io.spine.js.generate.imports;
 
 import com.google.common.collect.ImmutableList;
 import org.junit.jupiter.api.BeforeEach;
@@ -35,7 +35,7 @@
 import java.util.List;
 
 import static com.google.common.truth.Truth.assertThat;
-import static io.spine.js.generate.resolve.given.Given.importWithPath;
+import static io.spine.js.generate.imports.given.Given.importWithPath;
 
 @ExtendWith(TempDirectory.class)
 @DisplayName("JavaScript file should")
diff --git a/tools/proto-js-plugin/src/test/java/io/spine/js/generate/resolve/ResolveImportsTest.java b/tools/proto-js-plugin/src/test/java/io/spine/js/generate/imports/ResolveImportsTest.java
similarity index 95%
rename from tools/proto-js-plugin/src/test/java/io/spine/js/generate/resolve/ResolveImportsTest.java
rename to tools/proto-js-plugin/src/test/java/io/spine/js/generate/imports/ResolveImportsTest.java
index 87f5435e99..92d2696a54 100644
--- a/tools/proto-js-plugin/src/test/java/io/spine/js/generate/resolve/ResolveImportsTest.java
+++ b/tools/proto-js-plugin/src/test/java/io/spine/js/generate/imports/ResolveImportsTest.java
@@ -18,12 +18,14 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.js.generate.resolve;
+package io.spine.js.generate.imports;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.truth.IterableSubject;
 import io.spine.code.fs.js.Directory;
 import io.spine.js.generate.given.GivenProject;
+import io.spine.tools.code.structure.DirectoryPattern;
+import io.spine.tools.code.structure.ExternalModule;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 
@@ -33,14 +35,15 @@
 import java.util.List;
 
 import static com.google.common.truth.Truth.assertThat;
-import static io.spine.js.generate.resolve.given.Given.newModule;
 import static java.util.Arrays.asList;
 
 @DisplayName("ResolveImports task should")
 class ResolveImportsTest {
 
     private final Directory generatedProtoDir = GivenProject.mainProtoSources();
-    private final ExternalModule module = newModule("test-module", "root-dir");
+    private final ExternalModule module = new ExternalModule(
+            "test-module", ImmutableList.of(DirectoryPattern.of("root-dir"))
+    );
     private final Path tempDirectory = generatedProtoDir.path();
     private final Path testFile = tempDirectory.resolve("js/with-imports.js");
 
diff --git a/tools/proto-js-plugin/src/test/java/io/spine/js/generate/resolve/given/Given.java b/tools/proto-js-plugin/src/test/java/io/spine/js/generate/imports/given/Given.java
similarity index 58%
rename from tools/proto-js-plugin/src/test/java/io/spine/js/generate/resolve/given/Given.java
rename to tools/proto-js-plugin/src/test/java/io/spine/js/generate/imports/given/Given.java
index 7da7c8021c..6441e6337e 100644
--- a/tools/proto-js-plugin/src/test/java/io/spine/js/generate/resolve/given/Given.java
+++ b/tools/proto-js-plugin/src/test/java/io/spine/js/generate/imports/given/Given.java
@@ -18,20 +18,13 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.js.generate.resolve.given;
+package io.spine.js.generate.imports.given;
 
-import io.spine.code.fs.js.Directory;
-import io.spine.js.generate.resolve.DirectoryPattern;
-import io.spine.js.generate.resolve.ExternalModule;
-import io.spine.js.generate.resolve.ImportStatement;
+import io.spine.js.generate.imports.ImportStatement;
 
 import java.io.File;
-import java.nio.file.Path;
-import java.nio.file.Paths;
-import java.util.List;
 
 import static java.lang.String.format;
-import static java.util.Collections.singletonList;
 
 public class Given {
 
@@ -44,28 +37,7 @@ public static ImportStatement importWithPath(String path, File importOrigin) {
         return new ImportStatement(importText, importOrigin);
     }
 
-    public static Directory mainProtoRoot() {
-        return protoRoot("main");
-    }
-
-    public static Directory testProtoRoot() {
-        return protoRoot("test");
-    }
-
     public static String relativeImportPath() {
         return "../path-relative-to-parent.js";
     }
-
-    private static Directory protoRoot(String sourceSetName) {
-        Path path = Paths.get("src")
-                         .resolve(sourceSetName)
-                         .resolve("proto");
-        return Directory.at(path.toAbsolutePath());
-    }
-
-    public static ExternalModule newModule(String moduleName, String directoryPattern) {
-        DirectoryPattern pattern = DirectoryPattern.of(directoryPattern);
-        List<DirectoryPattern> patterns = singletonList(pattern);
-        return new ExternalModule(moduleName, patterns);
-    }
 }
diff --git a/tools/proto-js-plugin/src/test/java/io/spine/js/generate/imports/given/package-info.java b/tools/proto-js-plugin/src/test/java/io/spine/js/generate/imports/given/package-info.java
new file mode 100644
index 0000000000..c412a6f783
--- /dev/null
+++ b/tools/proto-js-plugin/src/test/java/io/spine/js/generate/imports/given/package-info.java
@@ -0,0 +1,31 @@
+/*
+ * Copyright 2020, TeamDev. All rights reserved.
+ *
+ * Redistribution and use in source and/or binary forms, with or without
+ * modification, must retain the above copyright notice and the following
+ * disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/**
+ * Contains test environment for components resolving script language imports.
+ */
+
+@CheckReturnValue
+@ParametersAreNonnullByDefault
+package io.spine.js.generate.imports.given;
+
+import com.google.errorprone.annotations.CheckReturnValue;
+
+import javax.annotation.ParametersAreNonnullByDefault;
diff --git a/tools/proto-js-plugin/src/test/java/io/spine/js/gradle/ExtensionTest.java b/tools/proto-js-plugin/src/test/java/io/spine/js/gradle/ExtensionTest.java
index f4bab09a43..25a5c01b55 100644
--- a/tools/proto-js-plugin/src/test/java/io/spine/js/gradle/ExtensionTest.java
+++ b/tools/proto-js-plugin/src/test/java/io/spine/js/gradle/ExtensionTest.java
@@ -22,7 +22,7 @@
 
 import io.spine.code.fs.js.DefaultJsProject;
 import io.spine.code.fs.js.Directory;
-import io.spine.js.generate.resolve.ExternalModule;
+import io.spine.tools.code.structure.ExternalModule;
 import org.gradle.api.Project;
 import org.gradle.api.plugins.PluginManager;
 import org.gradle.testfixtures.ProjectBuilder;
@@ -75,7 +75,8 @@ void defaultMainGenProto() {
         Directory directory = Extension.getMainGenProto(project);
         Directory expected = defaultProject.proto()
                                            .mainJs();
-        assertEquals(expected, directory);
+        assertThat(directory)
+                .isEqualTo(expected);
     }
 
     @Test
@@ -94,7 +95,8 @@ void defaultTestGenProto() {
         Directory directory = Extension.getTestGenProtoDir(project);
         Directory expected = defaultProject.proto()
                                            .testJs();
-        assertEquals(expected, directory);
+        assertThat(directory)
+                .isEqualTo(expected);
     }
 
     @Test
@@ -104,7 +106,8 @@ void customTestGenProto() {
         pluginExtension().testGenProtoDir = customPath;
         Directory directory = Extension.getTestGenProtoDir(project);
         Directory expected = Directory.at(Paths.get(customPath));
-        assertEquals(expected, directory);
+        assertThat(directory)
+                .isEqualTo(expected);
     }
 
     @Test
@@ -117,7 +120,8 @@ void defaultMainDescriptorSet() {
         File expected = mainDescriptors
                 .resolve(GROUP_ID + '_' + project.getName() + '_' + VERSION + ".desc")
                 .toFile();
-        assertEquals(expected, file);
+        assertThat(file)
+                .isEqualTo(expected);
     }
 
     @Test
@@ -127,7 +131,8 @@ void customMainDescriptorSet() {
         pluginExtension().mainDescriptorSetPath = customPath;
         File file = Extension.getMainDescriptorSet(project);
         File expected = new File(customPath);
-        assertEquals(expected, file);
+        assertThat(file)
+                .isEqualTo(expected);
     }
 
     @Test
@@ -140,7 +145,8 @@ void defaultTestDescriptorSet() {
         File expected = testDescriptors
                 .resolve(GROUP_ID + '_' + project.getName() + '_' + VERSION + "_test.desc")
                 .toFile();
-        assertEquals(expected, file);
+        assertThat(file)
+                .isEqualTo(expected);
     }
 
     @Test
@@ -150,14 +156,8 @@ void customTestDescriptorSet() {
         pluginExtension().testDescriptorSetPath = customPath;
         File file = Extension.getTestDescriptorSet(project);
         File expected = new File(customPath);
-        assertEquals(expected, file);
-    }
-
-    @Test
-    @DisplayName("include predefined Spine modules")
-    void includePredefinedModules() {
-        List<ExternalModule> modules = Extension.modules(project);
-        assertThat(modules).containsAtLeastElementsIn(Extension.predefinedModules());
+        assertThat(file)
+                .isEqualTo(expected);
     }
 
     @Test
@@ -167,8 +167,8 @@ void setModulesToResolve() {
         Map<String, List<String>> modulesExt = pluginExtension().modules;
         modulesExt.put(moduleName, emptyList());
         List<ExternalModule> modules = Extension.modules(project);
-        assertThat(modules).containsAtLeastElementsIn(Extension.predefinedModules());
-        assertThat(modules).contains(new ExternalModule(moduleName, emptyList()));
+        assertThat(modules)
+                .contains(new ExternalModule(moduleName, emptyList()));
     }
 
     private Extension pluginExtension() {
diff --git a/tools/tool-base/src/main/java/io/spine/code/fs/js/DirectoryReference.java b/tools/tool-base/src/main/java/io/spine/code/fs/DirectoryReference.java
similarity index 98%
rename from tools/tool-base/src/main/java/io/spine/code/fs/js/DirectoryReference.java
rename to tools/tool-base/src/main/java/io/spine/code/fs/DirectoryReference.java
index 9c37638dae..bc0b795169 100644
--- a/tools/tool-base/src/main/java/io/spine/code/fs/js/DirectoryReference.java
+++ b/tools/tool-base/src/main/java/io/spine/code/fs/DirectoryReference.java
@@ -18,7 +18,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.code.fs.js;
+package io.spine.code.fs;
 
 import com.google.common.base.Splitter;
 import com.google.common.collect.ImmutableList;
diff --git a/tools/tool-base/src/main/java/io/spine/code/fs/js/FileReference.java b/tools/tool-base/src/main/java/io/spine/code/fs/FileReference.java
similarity index 97%
rename from tools/tool-base/src/main/java/io/spine/code/fs/js/FileReference.java
rename to tools/tool-base/src/main/java/io/spine/code/fs/FileReference.java
index fc36a37d5f..017059f8c1 100644
--- a/tools/tool-base/src/main/java/io/spine/code/fs/js/FileReference.java
+++ b/tools/tool-base/src/main/java/io/spine/code/fs/FileReference.java
@@ -18,7 +18,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-package io.spine.code.fs.js;
+package io.spine.code.fs;
 
 import com.google.common.base.Splitter;
 import com.google.common.collect.ImmutableList;
@@ -29,7 +29,7 @@
 import static io.spine.util.Preconditions2.checkNotEmptyOrBlank;
 
 /**
- * A path to a file used in a JavaScript import statement.
+ * A path to a file used in an import statement.
  */
 public final class FileReference extends StringTypeValue {
 
diff --git a/tools/tool-base/src/main/java/io/spine/code/fs/js/FileName.java b/tools/tool-base/src/main/java/io/spine/code/fs/js/FileName.java
index 0268883f85..012bafc69f 100644
--- a/tools/tool-base/src/main/java/io/spine/code/fs/js/FileName.java
+++ b/tools/tool-base/src/main/java/io/spine/code/fs/js/FileName.java
@@ -26,6 +26,7 @@
 import com.google.common.collect.ImmutableList;
 import com.google.protobuf.Descriptors.FileDescriptor;
 import io.spine.code.AbstractFileName;
+import io.spine.code.fs.FileReference;
 
 import java.util.List;
 
diff --git a/tools/tool-base/src/test/java/io/spine/code/fs/js/DirectoryReferenceTest.java b/tools/tool-base/src/test/java/io/spine/code/fs/js/DirectoryReferenceTest.java
index a30e846e37..f51e562f74 100644
--- a/tools/tool-base/src/test/java/io/spine/code/fs/js/DirectoryReferenceTest.java
+++ b/tools/tool-base/src/test/java/io/spine/code/fs/js/DirectoryReferenceTest.java
@@ -20,6 +20,7 @@
 
 package io.spine.code.fs.js;
 
+import io.spine.code.fs.DirectoryReference;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 
diff --git a/tools/tool-base/src/test/java/io/spine/code/fs/js/FileReferenceTest.java b/tools/tool-base/src/test/java/io/spine/code/fs/js/FileReferenceTest.java
index 2b67d7ca6b..18ff66c56f 100644
--- a/tools/tool-base/src/test/java/io/spine/code/fs/js/FileReferenceTest.java
+++ b/tools/tool-base/src/test/java/io/spine/code/fs/js/FileReferenceTest.java
@@ -21,6 +21,7 @@
 package io.spine.code.fs.js;
 
 import com.google.common.testing.NullPointerTester;
+import io.spine.code.fs.FileReference;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 
diff --git a/version.gradle b/version.gradle
index 8d3d59d0b5..7add5bdb18 100644
--- a/version.gradle
+++ b/version.gradle
@@ -25,7 +25,7 @@
  * as we want to manage the versions in a single source.
  */
 
-final def SPINE_VERSION = '1.5.4'
+final def SPINE_VERSION = '1.5.5'
 
 ext {
     spineVersion = SPINE_VERSION