@Override
  public ContainerContext getContainerContext() {
    return this.containerContext;
  }
@param jobContext non-null job context
@param containerContext non-null framework container context
@param taskContext non-null framework task context
@param applicationContainerContextOptional optional application-defined container context
@param applicationTaskContextOptional optional application-defined task context
@param externalContextOptional optional external context
samza-core/src/main/java/org/apache/samza/context/ContextImpl.java