public void updateWriteMetrics(String source) {
    AzureBlobBasicMetrics sourceMetrics = sourceMetricsMap.get(source);
    if (sourceMetrics != null) {
      sourceMetrics.updateWriteMetrics();
    }
    incrementWriteMetrics();
  }
Increments the write metrics counters of aggregate, system and the source by 1.
Write metrics is for number of messages successfully written to the source.
@param source for which the message was sent.
samza-azure/src/main/java/org/apache/samza/system/azureblob/producer/AzureBlobSystemProducerMetrics.java