String generateIntermediate(CommentTracker ct) {
      if (TypeUtils.isJavaLangString(myLoopVariable.getType()) &&
          myMainJoinParts.size() == 1 &&
          myMainJoinParts.get(0) instanceof PsiReferenceExpression) {
        return "";
      }
      PsiElementFactory elementFactory = JavaPsiFacade.getElementFactory(myLoopVariable.getProject());
      String joinTransformation = getExpressionText(ct, myMainJoinParts);
      PsiExpression mapping = elementFactory.createExpressionFromText(joinTransformation, myLoopVariable);
      return StreamRefactoringUtil.generateMapOperation(myLoopVariable, null, mapping);
    }
String generateIntermediate(CommentTracker ct)