default <T> Future<T> inParallel(RunnableWithException runnable) {
    return inParallel(() -> {
      runnable.run();
      return null;
    });
  }
Executor that executes multiple tasks in parallel as part of the main body of concurrent test.

See {@link ConcurrentTestRunner}
geode-concurrency-test/src/main/java/org/apache/geode/test/concurrency/ParallelExecutor.java