@Override
  public void init(Context context) {
    ContainerContext containerContext = context.getContainerContext();
    metricsRegistry = containerContext.getContainerMetricsRegistry();
    inputEvents = metricsRegistry.newCounter(logicalOpId, TranslatorConstants.INPUT_EVENTS_NAME);
    inputEvents.clear();
  }
initializes the TranslatorOutputMetricsMapFunction before any message is processed
@param context the {@link Context} for this task
samza-sql/src/main/java/org/apache/samza/sql/translator/TranslatorInputMetricsMapFunction.java