@VisibleForTesting
  void setOperatorImplGraph(OperatorImplGraph operatorImplGraph) {
    this.operatorImplGraph = operatorImplGraph;
  }
Package private setter for private var operatorImplGraph to be used in TestStreamOperatorTask tests.
samza-core/src/main/java/org/apache/samza/task/StreamOperatorTask.java