code: public int incrementCounter(final StackifyError error, long epochMinute) {
  		if (error == null) {
  			throw new NullPointerException("StackifyError is null");
  		}
  
          ErrorItem baseError = getBaseError(error);
      	String uniqueKey = getUniqueKey(baseError);
  
          // get the counter for this error
      	
      	int count = 0;
  
          if (errorCounter.containsKey(uniqueKey)) {
          	
              // counter exists
  
          	MinuteCounter counter = errorCounter.get(uniqueKey);
  
              if (counter.getEpochMinute() == epochMinute) {
                  // counter exists for this current minute
                  // increment the counter
              	MinuteCounter incCounter = MinuteCounter.incrementCounter(counter);
              	errorCounter.put(uniqueKey, incCounter);
              	count = incCounter.getErrorCount();
              } else {
                  // counter did not exist for this minute
              	// overwrite the entry with a new one
              	MinuteCounter newCounter = MinuteCounter.newMinuteCounter(epochMinute);
              	errorCounter.put(uniqueKey, newCounter);
              	count = newCounter.getErrorCount();
              }
          } else {
              // counter did not exist so create a new one
          	MinuteCounter newCounter = MinuteCounter.newMinuteCounter(epochMinute);
          	errorCounter.put(uniqueKey, newCounter);
          	count = newCounter.getErrorCount();
          }
          
          return count;
      }
docs: Increments the counter for this error in the epoch minute specified
  @param error The error
  @param epochMinute The epoch minute
  @return The count for the error after it has been incremented