private org.box2d.proto.Box2D.PbVec2 buildParsed()
          throws com.google.protobuf.InvalidProtocolBufferException {
        org.box2d.proto.Box2D.PbVec2 result = buildPartial();
        if (!result.isInitialized()) {
          throw newUninitializedMessageException(
            result).asInvalidProtocolBufferException();
        }
        return result;
      }