code: protected boolean tryToClose() {
  		ByteBuffer blocker = blockerBuffer.get();
  		if (blocker == BUFFER_IS_CLOSED) {
  			return true;
  		}
  		if (blocker != null) {
  			return false;
  		}
  		boolean closed = blockerBuffer.compareAndSet(null, BUFFER_IS_CLOSED);
  		if (closed) {
  			closeResources();
  			return true;
  		}
  		return false;
  	}
docs: Tries to close this buffer.
  
  @return true, is closed (false = buffer is not empty)