docs: public static String unescape( String jcrExpression ) {
          Objects.requireNonNull(jcrExpression);
          if (jcrExpression.indexOf('\\') < 0) {
              return jcrExpression;
          }
          final StringBuilder buf = new StringBuilder(jcrExpression.length());
  
          for (CharacterIterator iter = new StringCharacterIterator(jcrExpression); iter.current() != CharacterIterator.DONE; iter.next()) {
              if (iter.current() == '\\' && iter.next() == '\\') {
                  buf.append('\\');
                  continue;
              }
              buf.append(iter.current());
          }
          return buf.toString();
      }