code: private <T> Future<T> execute(Promise<T> promise, Runnable runnable) {
          try {
              executor.execute(runnable);
          } catch (RejectedExecutionException ex) {
              // could be rejected due to resource starvation, report a failure
              promise.failure(ex);
          }
          return promise.future();
      }
docs: Executes the provided {@link Runnable} on the internal executor. <br>
  Any issues related to the internal executor are reported to the provided {@link Promise}
  
  @param promise
  The promise to fulfill once the work is finished
  @param runnable
  The runnable to execute in the executor
  @return The Future holding the response-to-be