feat: added UPPER_CASE_WITH_UNDERSCORES in FieldNamingPolicy

gson/src/main/java/com/google/gson/FieldNamingPolicy.java

@@ -75,6 +75,24 @@ public enum FieldNamingPolicy implements FieldNamingStrategy {
     }
   },
 
+  /**
+   * Using this naming policy with Gson will modify the Java Field name from its camel cased
+   * form to a upper case field name where each word is separated by an underscore (_).
+   *
+   * <p>Here's a few examples of the form "Java Field Name" ---&gt; "JSON Field Name":</p>
+   * <ul>
+   *   <li>someFieldName ---&gt; SOME_FIELD_NAME</li>
+   *   <li>_someFieldName ---&gt; _SOME_FIELD_NAME</li>
+   *   <li>aStringField ---&gt; A_STRING_FIELD</li>
+   *   <li>aURL ---&gt; A_U_R_L</li>
+   * </ul>
+   */
+  UPPER_CASE_WITH_UNDERSCORES() {
+    @Override public String translateName(Field f) {
+      return separateCamelCase(f.getName(), '_').toUpperCase(Locale.ENGLISH);
+    }
+  },
+
   /**
    * Using this naming policy with Gson will modify the Java Field name from its camel cased
    * form to a lower case field name where each word is separated by an underscore (_).

gson/src/test/java/com/google/gson/FieldNamingPolicyTest.java

@@ -67,7 +67,8 @@ class Dummy {
 
     FieldNamingPolicy[] policies = {
       FieldNamingPolicy.UPPER_CAMEL_CASE,
-      FieldNamingPolicy.UPPER_CAMEL_CASE_WITH_SPACES
+      FieldNamingPolicy.UPPER_CAMEL_CASE_WITH_SPACES,
+      FieldNamingPolicy.UPPER_CASE_WITH_UNDERSCORES,
     };
 
     Field field = Dummy.class.getDeclaredField("i");

gson/src/test/java/com/google/gson/functional/FieldNamingTest.java

@@ -21,6 +21,7 @@
 import static com.google.gson.FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES;
 import static com.google.gson.FieldNamingPolicy.UPPER_CAMEL_CASE;
 import static com.google.gson.FieldNamingPolicy.UPPER_CAMEL_CASE_WITH_SPACES;
+import static com.google.gson.FieldNamingPolicy.UPPER_CASE_WITH_UNDERSCORES;
 
 import com.google.gson.FieldNamingPolicy;
 import com.google.gson.Gson;
@@ -53,6 +54,14 @@ public void testUpperCamelCaseWithSpaces() {
         gson.toJson(new TestNames()).replace('\"', '\''));
   }
 
+  public void testUpperCaseWithUnderscores() {
+    Gson gson = getGsonWithNamingPolicy(UPPER_CASE_WITH_UNDERSCORES);
+    assertEquals("{'LOWER_CAMEL':1,'UPPER_CAMEL':2,'_LOWER_CAMEL_LEADING_UNDERSCORE':3," +
+        "'__UPPER_CAMEL_LEADING_UNDERSCORE':4,'LOWER_WORDS':5,'U_P_P_E_R__W_O_R_D_S':6," +
+        "'annotatedName':7,'LOWER_ID':8,'_9':9}",
+        gson.toJson(new TestNames()).replace('\"', '\''));
+  }
+
   public void testLowerCaseWithUnderscores() {
     Gson gson = getGsonWithNamingPolicy(LOWER_CASE_WITH_UNDERSCORES);
     assertEquals("{'lower_camel':1,'upper_camel':2,'_lower_camel_leading_underscore':3," +

gson/src/test/java/com/google/gson/functional/NamingPolicyTest.java

@@ -141,6 +141,22 @@ public void testGsonWithUpperCamelCaseSpacesPolicyDeserialiation() {
     assertEquals("someValue", deserializedObject.someConstantStringInstanceField);
   }
 
+  public void testGsonWithUpperCaseUnderscorePolicySerialization() {
+    Gson gson = builder.setFieldNamingPolicy(FieldNamingPolicy.UPPER_CASE_WITH_UNDERSCORES)
+        .create();
+    StringWrapper target = new StringWrapper("blah");
+    assertEquals("{\"SOME_CONSTANT_STRING_INSTANCE_FIELD\":\""
+        + target.someConstantStringInstanceField + "\"}", gson.toJson(target));
+  }
+
+  public void testGsonWithUpperCaseUnderscorePolicyDeserialiation() {
+    Gson gson = builder.setFieldNamingPolicy(FieldNamingPolicy.UPPER_CASE_WITH_UNDERSCORES)
+        .create();
+    String target = "{\"SOME_CONSTANT_STRING_INSTANCE_FIELD\":\"someValue\"}";
+    StringWrapper deserializedObject = gson.fromJson(target, StringWrapper.class);
+    assertEquals("someValue", deserializedObject.someConstantStringInstanceField);
+  }
+
   public void testDeprecatedNamingStrategy() throws Exception {
     Gson gson = builder.setFieldNamingStrategy(new UpperCaseNamingStrategy()).create();
     ClassWithDuplicateFields target = new ClassWithDuplicateFields(10);