code: @Override
  	public void computeUnclosedBranchStack() {
  		if (this.openBranches != null) {
  			return;
  		}
  
  		// we need to track open branches even in the sinks, because they get "closed" when
  		// we build a single "root" for the data flow plan
  		addClosedBranches(getPredecessorNode().closedBranchingNodes);
  		this.openBranches = getPredecessorNode().getBranchesForParent(this.input);
  	}
docs: --------------------------------------------------------------------------------------------