public CauseItem merge(CauseItem other) {
      if (this.equals(other)) return this;
      if (Objects.equals(this.myTarget, other.myTarget)) {
        if (myChildren.equals(other.myChildren)) {
          DfaProblemType mergedProblem = myProblem.tryMerge(other.myProblem);
          if (mergedProblem != null) {
            return new CauseItem(myChildren, mergedProblem, myTarget);
          }
        }
        if (getProblemName().equals(other.getProblemName())) {
          if (tryMergeChildren(other.myChildren)) return this;
          if (other.tryMergeChildren(this.myChildren)) return other;
        }
      }
      return null;
    }
public CauseItem merge(CauseItem other)