code: protected static void addFileListPropertyValue(CmsObject cms, Element valueElement, String propValue) {
  
          // resource list value
          Element filelistElem = valueElement.addElement(CmsXmlContentProperty.XmlNode.FileList.name());
          for (String strId : CmsStringUtil.splitAsList(propValue, CmsXmlContentProperty.PROP_SEPARATOR)) {
              try {
                  Element fileValueElem = filelistElem.addElement(CmsXmlContentProperty.XmlNode.Uri.name());
                  CmsVfsFileValueBean fileValue = getFileValueForIdOrUri(cms, strId);
                  // HACK: here we assume weak relations, but it would be more robust to check it, with smth like:
                  // type = xmlContent.getContentDefinition().getContentHandler().getRelationType(fileValueElem.getPath());
                  CmsRelationType type = CmsRelationType.XML_WEAK;
                  CmsXmlVfsFileValue.fillEntry(fileValueElem, fileValue.getId(), fileValue.getPath(), type);
              } catch (CmsException e) {
                  // should never happen
                  LOG.error(e.getLocalizedMessage(), e);
              }
          }
      }
docs: Adds the XML for a property value of a property of type 'vfslist' to the DOM.<p>
  
  @param cms the current CMS context
  @param valueElement the element to which the vfslist property value should be added
  @param propValue the property value which should be saved