docs: private void addAdditionalFields() {
  
          /*
           * Add fields from opencms-search.xml (Lucene fields)
           */
          for (CmsSearchField field : getFields()) {
              if (field instanceof CmsLuceneField) {
                  CmsSolrField newSolrField = new CmsSolrField((CmsLuceneField)field);
                  m_solrFields.put(newSolrField.getName(), newSolrField);
              }
          }
  
          /*
           * Add the content fields (multiple for contents with more than one locale)
           */
          // add the content_<locale> fields to this configuration
          CmsSolrField solrField = new CmsSolrField(CmsSearchField.FIELD_CONTENT, null, null, null);
          solrField.addMapping(
              new CmsSearchFieldMapping(CmsSearchFieldMappingType.CONTENT, CmsSearchField.FIELD_CONTENT));
          m_solrFields.put(solrField.getName(), solrField);
          for (Locale locale : OpenCms.getLocaleManager().getAvailableLocales()) {
              solrField = new CmsSolrField(
                  CmsSearchFieldConfiguration.getLocaleExtendedName(CmsSearchField.FIELD_CONTENT, locale),
                  Collections.singletonList(locale.toString() + CmsSearchField.FIELD_EXCERPT),
                  locale,
                  null);
              solrField.addMapping(
                  new CmsSearchFieldMapping(CmsSearchFieldMappingType.CONTENT, CmsSearchField.FIELD_CONTENT));
              m_solrFields.put(solrField.getName(), solrField);
          }
  
          /*
           * Fields filled within appendFields
           */
          CmsSolrField sfield = new CmsSolrField(CmsSearchField.FIELD_MIMETYPE, null, null, null);
          m_solrFields.put(sfield.getName(), sfield);
  
          sfield = new CmsSolrField(CmsSearchField.FIELD_FILENAME, null, null, null);
          m_solrFields.put(sfield.getName(), sfield);
  
          sfield = new CmsSolrField(CmsSearchField.FIELD_VERSION, null, null, null);
          m_solrFields.put(sfield.getName(), sfield);
  
          sfield = new CmsSolrField(CmsSearchField.FIELD_SEARCH_CHANNEL, null, null, null);
          m_solrFields.put(sfield.getName(), sfield);
  
          /*
           * Fields with mapping
           */
          sfield = new CmsSolrField(CmsSearchField.FIELD_STATE, null, null, null);
          CmsSearchFieldMapping map = new CmsSearchFieldMapping(
              CmsSearchFieldMappingType.ATTRIBUTE,
              CmsSearchField.FIELD_STATE);
          sfield.addMapping(map);
          m_solrFields.put(sfield.getName(), sfield);
  
          sfield = new CmsSolrField(CmsSearchField.FIELD_USER_LAST_MODIFIED, null, null, null);
          map = new CmsSearchFieldMapping(CmsSearchFieldMappingType.ATTRIBUTE, CmsSearchField.FIELD_USER_LAST_MODIFIED);
          sfield.addMapping(map);
          m_solrFields.put(sfield.getName(), sfield);
  
          sfield = new CmsSolrField(CmsSearchField.FIELD_USER_CREATED, null, null, null);
          map = new CmsSearchFieldMapping(CmsSearchFieldMappingType.ATTRIBUTE, CmsSearchField.FIELD_USER_CREATED);
          sfield.addMapping(map);
          m_solrFields.put(sfield.getName(), sfield);
  
          sfield = new CmsSolrField(CmsSearchField.FIELD_META, null, null, null);
          map = new CmsSearchFieldMapping(CmsSearchFieldMappingType.PROPERTY, CmsPropertyDefinition.PROPERTY_TITLE);
          sfield.addMapping(map);
          map = new CmsSearchFieldMapping(CmsSearchFieldMappingType.PROPERTY, CmsPropertyDefinition.PROPERTY_DESCRIPTION);
          sfield.addMapping(map);
          map = new CmsSearchFieldMapping(CmsSearchFieldMappingType.ATTRIBUTE, I_CmsXmlConfiguration.A_NAME);
          sfield.addMapping(map);
          m_solrFields.put(sfield.getName(), sfield);
  
          sfield = new CmsSolrField(CmsSearchField.FIELD_SEARCH_EXCLUDE, null, null, null);
          map = new CmsSearchFieldMapping(
              CmsSearchFieldMappingType.PROPERTY_SEARCH,
              CmsPropertyDefinition.PROPERTY_SEARCH_EXCLUDE);
          sfield.addMapping(map);
          m_solrFields.put(sfield.getName(), sfield);
  
          sfield = new CmsSolrField(CmsSearchField.FIELD_CONTAINER_TYPES, null, null, null);
          map = new CmsSearchFieldMapping(
              CmsSearchFieldMappingType.DYNAMIC,
              "org.opencms.search.galleries.CmsGallerySearchFieldMapping");
          map.setDefaultValue("container_types");
          sfield.addMapping(map);
          m_solrFields.put(sfield.getName(), sfield);
  
          sfield = new CmsSolrField(CmsSearchField.FIELD_ADDITIONAL_INFO, null, null, null);
          map = new CmsSearchFieldMapping(
              CmsSearchFieldMappingType.DYNAMIC,
              "org.opencms.search.galleries.CmsGallerySearchFieldMapping");
          map.setDefaultValue("additional_info");
          sfield.addMapping(map);
          m_solrFields.put(sfield.getName(), sfield);
      }