private static @Nullable JsonStringLiteral getSingleElementFromSelectionOrNull(PsiFile file, int start, int end) {
    final PsiElement element = file.findElementAt(start);
    final JsonStringLiteral literalExpression = PsiTreeUtil.getParentOfType(element, JsonStringLiteral.class);
    if (literalExpression == null) return null;
    TextRange textRange = literalExpression.getTextRange();
    if (start <= textRange.getStartOffset() || end >= textRange.getEndOffset()) return null;
    String text = literalExpression.getText();
    if (!text.startsWith("\"") || !text.endsWith("\"")) return null;
    return literalExpression;
  }
private static @Nullable JsonStringLiteral getSingleElementFromSelectionOrNull(PsiFile file, int start, int end)