public String getTaskMode() {
    return getMessageValue(TASKMODE_KEY);
  }
SetTaskModeMapping is used to set the task to taskMode mapping information.
@param source              the source of the message
@param taskName                 the taskName which is used to persist the message
@param taskMode            the taskMode of the task
samza-core/src/main/java/org/apache/samza/coordinator/stream/messages/SetTaskModeMapping.java