code: CmsFlexCacheKey getKey(String resource) {
  
          if (!isEnabled()) {
              return null;
          }
          Object o = m_keyCache.get(resource);
          if (o != null) {
              if (LOG.isDebugEnabled()) {
                  LOG.debug(Messages.get().getBundle().key(Messages.LOG_FLEXCACHEKEY_FOUND_1, resource));
              }
              return ((CmsFlexCacheVariation)o).m_key;
          } else {
              if (LOG.isDebugEnabled()) {
                  LOG.debug(Messages.get().getBundle().key(Messages.LOG_FLEXCACHEKEY_NOT_FOUND_1, resource));
              }
              return null;
          }
      }
docs: Returns the CmsFlexCacheKey data structure for a given resource name.<p>
  
  @param resource the resource name for which to look up the key for
  @return the CmsFlexCacheKey data structure found for the resource