code: public void cancelStackTraceSample(int sampleId, Throwable cause) {
  		synchronized (lock) {
  			if (isShutDown) {
  				return;
  			}
  
  			PendingStackTraceSample sample = pendingSamples.remove(sampleId);
  			if (sample != null) {
  				if (cause != null) {
  					LOG.info("Cancelling sample " + sampleId, cause);
  				} else {
  					LOG.info("Cancelling sample {}", sampleId);
  				}
  
  				sample.discard(cause);
  				rememberRecentSampleId(sampleId);
  			}
  		}
  	}
docs: Cancels a pending sample.
  
  @param sampleId ID of the sample to cancel.
  @param cause Cause of the cancelling (can be <code>null</code>).