code: void addCredit(InputChannelID receiverId, int credit) throws Exception {
  		if (fatalError) {
  			return;
  		}
  
  		NetworkSequenceViewReader reader = allReaders.get(receiverId);
  		if (reader != null) {
  			reader.addCredit(credit);
  
  			enqueueAvailableReader(reader);
  		} else {
  			throw new IllegalStateException("No reader for receiverId = " + receiverId + " exists.");
  		}
  	}
docs: Adds unannounced credits from the consumer and enqueues the corresponding reader for this
  consumer (if not enqueued yet).
  
  @param receiverId The input channel id to identify the consumer.
  @param credit The unannounced credits of the consumer.