@Override
 protected void doFix(Project project, ProblemDescriptor descriptor) {
   final TextRange textRange = descriptor.getTextRangeInElement();
   final PsiElement element = descriptor.getPsiElement();
   if (!(element instanceof PsiFile)) {
     return;
   }
   final PsiFile file = (PsiFile) element;
   final Document document = PsiDocumentManager.getInstance(project).getDocument(file);
   if (document == null) {
     return;
   }
   document.replaceString(
       textRange.getStartOffset(), textRange.getEndOffset(), String.valueOf(c));
 }