@Override
  public void setStartingOffset(SystemStreamPartition systemStreamPartition, String offset) {
    this.offsetManager.setStartingOffset(this.taskModel.getTaskName(), systemStreamPartition, offset);
  }
This class provides the implementation for the public {@link TaskContext} interface.
It also allows us to pass certain internal Samza components around so that the implementation of the high-level API
can use them (see InternalTaskContext for some more details).
samza-core/src/main/java/org/apache/samza/context/TaskContextImpl.java