public Integer getContainerThreadPoolSize() {
    return (Integer) getFromMetricsMessage(GROUP_NAME_FOR_DIAGNOSTICS_MANAGER, CONTAINER_THREAD_POOL_SIZE_METRIC_NAME);
  }
Check if the message has no contents.
@return True if the message is empty, false otherwise.
samza-core/src/main/scala/org/apache/samza/diagnostics/DiagnosticsStreamMessage.java