private CodeBlock mapMethodBody(TypeMirror keyType, TypeMirror valueType) {
      return forEachMapEntryMethodBody(keyType, valueType, "value");
    }
Parameter object to simplify the branches of {@link #format(CodeBlock, CodeBlock,
TypeMirror)} that call a delegate method.
value/src/main/java/com/google/auto/value/extension/toprettystring/processor/ToPrettyStringExtension.java