May put any kind of extra field value

endpoints-framework/src/main/java/com/google/api/server/spi/ServiceException.java

@@ -153,6 +153,26 @@ public ServiceException putExtraField(String fieldName, Number value) {
     return putExtraFieldInternal(fieldName, value);
   }
 
+  /**
+   * Associates to this exception an extra field as a field name/value pair. If a field
+   * with the same name was previously set, the old value is replaced by the specified
+   * value.<br>
+   * This unsafe version accepts any POJO as is:
+   * <ul>
+   * <li>the object should be serializable</li>
+   * <li>no defensive copy nor conversion are made. So {@code value} should not be modified
+   * or reused after the call of this method.</li>
+   * </ul>
+   * These constraints must be taken into consideration when overriding this method.
+   * @return this
+   * @throws NullPointerException if {@code fieldName} is {@code null}.
+   * @throws IllegalArgumentException if {@code fieldName} is one of the reserved field
+   *         names {@link #EXTRA_FIELDS_RESERVED_NAMES}.
+   */
+  protected ServiceException putExtraFieldUnsafe(String fieldName, Object value) {
+    return putExtraFieldInternal(fieldName, value);
+  }
+
   private ServiceException putExtraFieldInternal(String fieldName, Object value) {
     Preconditions.checkNotNull(fieldName);
     Preconditions.checkArgument(!EXTRA_FIELDS_RESERVED_NAMES.contains(fieldName), "The field name '%s' is reserved", fieldName);

endpoints-framework/src/test/java/com/google/api/server/spi/response/RestResponseResultWriterTest.java

@@ -32,6 +32,11 @@
 import org.skyscreamer.jsonassert.JSONAssert;
 import org.springframework.mock.web.MockHttpServletResponse;
 
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
 /**
  * Tests for {@link RestResponseResultWriter}.
  */
@@ -269,4 +274,79 @@ public void writeError_extraFields() throws Exception {
     writer.writeError(serviceException);
     JSONAssert.assertEquals(expectedError, response.getContentAsString(), true);
   }
+
+  @Test
+  public void writeError_extraFieldsUnsafe() throws Exception {
+
+    MockHttpServletResponse response = new MockHttpServletResponse();
+    RestResponseResultWriter writer = new RestResponseResultWriter(response, null, true /* prettyPrint */,
+            true /* addContentLength */, true /* enableExceptionCompatibility */);
+
+    TestServiceExceptionExtraFieldUnsafe serviceException = new TestServiceExceptionExtraFieldUnsafe(400, "customMessage", "customReason", "customDomain");
+
+    // Extra field array
+    Boolean[] booleans = new Boolean[] { TRUE, FALSE, TRUE };
+
+    // Extra field List
+    List<String> stringList = Arrays.asList("First", "Second", "Last");
+
+    // Extra field Map
+    Map<Integer, TestValue> map = new HashMap<>();
+    map.put(1, new TestValue("Alice", 7, TestEnum.VALUE1));
+    map.put(2, new TestValue("Bob", 12, TestEnum.VALUE2));
+    map.put(3, new TestValue("Clark", 31, TestEnum.VALUE3));
+
+    serviceException.putExtraFieldUnsafe("someExtraNull", null)
+                    .putExtraFieldUnsafe("someExtraArray", booleans)
+                    .putExtraFieldUnsafe("someExtraList", stringList)
+                    .putExtraFieldUnsafe("someExtraMap", map);
+
+    String expectedError = "{\"error\": {\"errors\": [{" +
+            "  \"domain\": \"customDomain\"," +
+            "  \"reason\": \"customReason\"," +
+            "  \"message\": \"customMessage\"," +
+            "  \"someExtraNull\": null," +
+            "  \"someExtraArray\": [true, false, true]," +
+            "  \"someExtraList\": [\"First\", \"Second\", \"Last\"]," +
+            "  \"someExtraMap\": {" +
+            "    \"1\": {\"name\": \"Alice\", \"age\": 7, \"testEnum\": \"VALUE1\"}," +
+            "    \"2\": {\"name\": \"Bob\", \"age\": 12, \"testEnum\": \"VALUE2\"}," +
+            "    \"3\": {\"name\": \"Clark\", \"age\": 31, \"testEnum\": \"VALUE3\"}" +
+            "  }" +
+            " }]," +
+            " \"code\": 400," +
+            " \"message\": \"customMessage\"" +
+            "}}";
+
+    writer.writeError(serviceException);
+    JSONAssert.assertEquals(expectedError, response.getContentAsString(), true);
+  }
+
+  enum TestEnum {
+    VALUE1, VALUE2, VALUE3;
+  }
+
+  class TestValue {
+    public String name;
+    public int age;
+    public TestEnum testEnum;
+
+    TestValue(String name, int age, TestEnum testEnum) {
+      this.name = name;
+      this.age = age;
+      this.testEnum = testEnum;
+    }
+  }
+
+  class TestServiceExceptionExtraFieldUnsafe extends ServiceException {
+
+    TestServiceExceptionExtraFieldUnsafe(int statusCode, String statusMessage, String reason, String domain) {
+      super(statusCode, statusMessage, reason, domain);
+    }
+
+    @Override
+    public TestServiceExceptionExtraFieldUnsafe putExtraFieldUnsafe(String fieldName, Object value) {
+      return (TestServiceExceptionExtraFieldUnsafe) super.putExtraFieldUnsafe(fieldName, value);
+    }
+  }
 }