docs: public static ParserConfiguration[] filterExisting(final List<? extends ParserConfiguration> parsers) {
          List<ParserConfiguration> existing = Lists.newArrayList();
          for (ParserConfiguration parser : parsers) {
              if (ParserRegistry.exists(parser.getParserName())) {
                  existing.add(parser);
              }
          }
          return existing.toArray(new ParserConfiguration[existing.size()]);
      }