@Nullable
    private static String computeConstant(@NotNull List<PsiExpression> joinParts) {
      StringBuilder sb = new StringBuilder();
      for (PsiExpression expression : joinParts) {
        String constant = computeConstant(expression);
        if(constant == null) return null;
        sb.append(constant);
      }
      return sb.toString();
    }
@Nullable
    private static String computeConstant(@NotNull List<PsiExpression> joinParts)