diff --git a/build.gradle b/build.gradle
index 5e4842c..c4fd8e7 100644
--- a/build.gradle
+++ b/build.gradle
@@ -61,9 +61,11 @@ publishing {
     repositories {
         maven {
             url "https://oss.sonatype.org/service/local/staging/deploy/maven2"
-            credentials {
-                username sonatypeUsername
-                password sonatypePassword
+            if (project.hasProperty('sonatypeUsername') && project.hasProperty('sonatypePassword')) {
+                credentials {
+                    username sonatypeUsername
+                    password sonatypePassword
+                }
             }
         }
     }
diff --git a/src/main/java/io/gitgub/eaxdev/jsonresume/validator/model/BasicInfo.java b/src/main/java/io/gitgub/eaxdev/jsonresume/validator/model/BasicInfo.java
index 9572cbf..5bbe958 100644
--- a/src/main/java/io/gitgub/eaxdev/jsonresume/validator/model/BasicInfo.java
+++ b/src/main/java/io/gitgub/eaxdev/jsonresume/validator/model/BasicInfo.java
@@ -1,6 +1,5 @@
 package io.gitgub.eaxdev.jsonresume.validator.model;
 
-import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonUnwrapped;
 import lombok.Getter;
diff --git a/src/main/java/io/gitgub/eaxdev/jsonresume/validator/model/Education.java b/src/main/java/io/gitgub/eaxdev/jsonresume/validator/model/Education.java
index 2375137..0082837 100644
--- a/src/main/java/io/gitgub/eaxdev/jsonresume/validator/model/Education.java
+++ b/src/main/java/io/gitgub/eaxdev/jsonresume/validator/model/Education.java
@@ -4,8 +4,6 @@
 import lombok.Getter;
 import lombok.Setter;
 
-import java.time.LocalDate;
-
 @Getter
 @Setter
 public class Education extends Period {
diff --git a/src/main/java/io/gitgub/eaxdev/jsonresume/validator/model/Period.java b/src/main/java/io/gitgub/eaxdev/jsonresume/validator/model/Period.java
index 74e241a..502191f 100644
--- a/src/main/java/io/gitgub/eaxdev/jsonresume/validator/model/Period.java
+++ b/src/main/java/io/gitgub/eaxdev/jsonresume/validator/model/Period.java
@@ -4,9 +4,13 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
 import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateDeserializer;
+import lombok.Getter;
+import lombok.Setter;
 
 import java.time.LocalDate;
 
+@Getter
+@Setter
 abstract class Period {
 
     @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd")
diff --git a/src/main/java/io/gitgub/eaxdev/jsonresume/validator/model/Volunteer.java b/src/main/java/io/gitgub/eaxdev/jsonresume/validator/model/Volunteer.java
index 5273792..7415ea6 100644
--- a/src/main/java/io/gitgub/eaxdev/jsonresume/validator/model/Volunteer.java
+++ b/src/main/java/io/gitgub/eaxdev/jsonresume/validator/model/Volunteer.java
@@ -5,8 +5,6 @@
 import lombok.Setter;
 import org.hibernate.validator.constraints.URL;
 
-import java.time.LocalDate;
-
 @Getter
 @Setter
 public class Volunteer extends Period {
diff --git a/src/main/java/io/gitgub/eaxdev/jsonresume/validator/model/Work.java b/src/main/java/io/gitgub/eaxdev/jsonresume/validator/model/Work.java
index 3276b78..6f2b8f7 100644
--- a/src/main/java/io/gitgub/eaxdev/jsonresume/validator/model/Work.java
+++ b/src/main/java/io/gitgub/eaxdev/jsonresume/validator/model/Work.java
@@ -5,8 +5,6 @@
 import lombok.Setter;
 import org.hibernate.validator.constraints.URL;
 
-import java.time.LocalDate;
-
 @Getter
 @Setter
 public class Work extends Period {
diff --git a/src/main/java/io/gitgub/eaxdev/jsonresume/validator/validator/BeanValidationDeserializer.java b/src/main/java/io/gitgub/eaxdev/jsonresume/validator/validator/BeanValidationDeserializer.java
index aaaa3c3..262c2a3 100644
--- a/src/main/java/io/gitgub/eaxdev/jsonresume/validator/validator/BeanValidationDeserializer.java
+++ b/src/main/java/io/gitgub/eaxdev/jsonresume/validator/validator/BeanValidationDeserializer.java
@@ -13,7 +13,7 @@
 
 public class BeanValidationDeserializer extends BeanDeserializer {
 
-    private final static ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
+    private static final ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
 
     private final Validator validator = factory.getValidator();
 
@@ -30,7 +30,7 @@ public Object deserialize(JsonParser p, DeserializationContext ctx) throws IOExc
 
     private void validate(final Object instance) {
         final Set<ConstraintViolation<Object>> violations = validator.validate(instance);
-        if (violations.size() > 0) {
+        if (!violations.isEmpty()) {
             final String message = "JSON is not valid. Reasons (" + violations.size() + "): ";
             final String errorMessages = violations.stream()
                     .map(v -> "Value `" + v.getInvalidValue() + "` is not correct. " + v.getMessage())
diff --git a/src/test/java/io/gitgub/eaxdev/jsonresume/validator/BasicTest.java b/src/test/java/io/gitgub/eaxdev/jsonresume/validator/BasicTest.java
index c15ddaa..94eb7c3 100644
--- a/src/test/java/io/gitgub/eaxdev/jsonresume/validator/BasicTest.java
+++ b/src/test/java/io/gitgub/eaxdev/jsonresume/validator/BasicTest.java
@@ -11,7 +11,7 @@
 
 import static org.junit.jupiter.api.Assertions.*;
 
-public class BasicTest {
+class BasicTest {
 
     @Test
     void basicUsage() throws IOException, JsonResumeParseException {