@Nullable
      private static List<PsiExpression> extractDelimiter(PsiIfStatement ifStatement) {
        PsiStatement thenBranch = ifStatement.getThenBranch();
        if (thenBranch == null) return null;
        List<PsiStatement> delimiterAppendStatements = Arrays.asList(ControlFlowUtils.unwrapBlock(thenBranch));
        List<PsiExpression> delimiterJoinParts = extractJoinParts(delimiterAppendStatements);
        if (delimiterJoinParts == null) return null;
        if(computeConstant(delimiterJoinParts) == null) return null;
        return delimiterJoinParts;
      }
@Nullable
      private static List<PsiExpression> extractDelimiter(PsiIfStatement ifStatement)