code: public static <T> ParallelBatch<T> of(final TraceContext context, Promise<T>... promises) {
      return of(context, Arrays.asList(promises));
    }
docs: Create a {@link TracedParallelBatch} for list of {@link Promise}s,
  with the specified trace context.
  
  @param context the trace context.
  @param promises vararg containing a list of {@link Promise}s.
  @param <T> the type of value produced by each promise
  
  @return an instance of {@link ParallelBatch}.