code: public boolean evaluate(final LoggingEvent event, Map matches) {
      Object p2 = RESOLVER.getValue(field, event);
  
      boolean result = (p2 != null) && p2.toString().equals(value);
      if (result && matches != null) {
          Set entries = (Set) matches.get(field.toUpperCase());
          if (entries == null) {
              entries = new HashSet();
              matches.put(field.toUpperCase(), entries);
          }
          entries.add(value);
      }
      return result;
    }
docs: {@inheritDoc}