code: @CheckReturnValue
    public static <ReqT, RespT> Builder<ReqT, RespT> newBuilder(
        Marshaller<ReqT> requestMarshaller, Marshaller<RespT> responseMarshaller) {
      return new Builder<ReqT, RespT>()
          .setRequestMarshaller(requestMarshaller)
          .setResponseMarshaller(responseMarshaller);
    }
docs: Creates a new builder for a {@link MethodDescriptor}.
  
  @since 1.1.0