code: protected Object resolveExistsResource(String exp, Map<String, ? extends Object> contextMap, LaContainer container,
              Class<?> resultType) {
          if (exp.startsWith(EXISTS_BEGIN) && exp.endsWith(EXISTS_END)) {
              final String path = exp.substring(EXISTS_BEGIN.length(), exp.lastIndexOf(EXISTS_END));
              if (!path.contains(SQ)) {
                  return LdiResourceUtil.exists(path);
              }
          }
          return null;
      }
docs: ===============