code: public static ConstrainedExecutorService newConstrainedExecutor(
        String name,
        int maxConcurrency,
        int queueSize,
        Executor executor) {
      return new ConstrainedExecutorService(
          name,
          maxConcurrency,
          executor,
          new LinkedBlockingQueue<Runnable>(queueSize));
    }
docs: Factory method to create a new {@code ConstrainedExecutorService} with an unbounded
  {@link LinkedBlockingQueue} queue.
  @param name Friendly name to identify the executor in logging and reporting.
  @param maxConcurrency Maximum number of tasks to execute in parallel on the delegate executor.
  @param queueSize Number of items that can be queued before new submissions are rejected.
  @param executor Delegate executor for actually running tasks.
  @return new {@code ConstrainedExecutorService} instance.