code: @NullSafe
    public static boolean isTerminated(Thread thread) {
      return (thread != null && Thread.State.TERMINATED.equals(thread.getState()));
    }
docs: Determines whether the specified Thread has been terminated (stopped).
  
  @param thread the Thread to evaluate.
  @return a boolean value indicating whether the Thread has been terminated.
  @see java.lang.Thread#getState()
  @see java.lang.Thread.State#TERMINATED