code: protected void combineContentItem(
          String itemValue,
          String itemKey,
          StringBuffer content,
          Map<String, String> contentItems) {
  
          if (CmsStringUtil.isNotEmpty(itemValue)) {
              contentItems.put(itemKey, itemValue);
              content.append('\n');
              content.append(itemValue);
          }
      }
docs: Combines a meta information item extracted from the document with the main content buffer and
  also stores the individual information as item in the Map of content items.<p>
  
  @param itemValue the value of the item to store
  @param itemKey the key in the Map of content items
  @param content a buffer where to append the content item
  @param contentItems the Map of individual content items