code: @Override
      public String getUserFacingMessage() {
          final StringBuilder bldr = new StringBuilder();
  
          String rl = getResourceLocation();
          String pref = getPrefix();
          String val = getValue();
          bldr.append("symbol ");
          bldr.append(val);
          bldr.append(" does not exist in ");
          if (hasLength(pref)) {
              bldr.append(pref);
          } else {
              bldr.append(rl);
          }
          return bldr.toString();
      }
docs: {@inheritDoc}