code: public Set<String> getCachedResources(CmsObject cms) {
  
          if (!isEnabled() || !OpenCms.getRoleManager().hasRole(cms, CmsRole.WORKPLACE_MANAGER)) {
              return null;
          }
          return synchronizedCopyKeys(m_keyCache);
      }
docs: Returns a set of all cached resource names.<p>
  
  Useful if you want to show a list of all cached resources,
  like on the FlexCache administration page.<p>
  
  Only users with administrator permissions are allowed
  to perform this operation.<p>
  
  @param cms the CmsObject used for user authorization
  @return a Set of cached resource names (which are of type String)