code: public Runnable execute(Runnable command, long timeoutInMillis) throws InterruptedException, IllegalStateException {
          try {
              return execute(command, WAIT_WHEN_QUEUE_IS_FULL, timeoutInMillis);
          } catch (ThreadPoolQueueIsFullException e) {
              // we should not get here.
              // Alex Ffdc.log(e, this, ThreadPool.class.getName(), "855"); // D477704.2
              return null;
          }
      }
docs: Arrange for the given command to be executed by a thread in this
  pool. If the pools internal request buffer is full, the call
  will block for at most timeoutInMillis milliseconds.
  
  @param command
  - the work to be dispatched.
  @param timeoutInMillis
  - the amount of time to block and
  wait if the request buffer is full.
  @return the command if it was, indeed queued to the pool or
  null if the request timed out.