docs: void putKey(CmsFlexCacheKey key) {
  
          if (!isEnabled()) {
              return;
          }
          Object o = m_keyCache.get(key.getResource());
          if (o == null) {
              // No variation map for this resource yet, so create one
              CmsFlexCacheVariation variationMap = new CmsFlexCacheVariation(key);
              m_keyCache.put(key.getResource(), variationMap);
              if (LOG.isDebugEnabled()) {
                  LOG.debug(Messages.get().getBundle().key(Messages.LOG_FLEXCACHE_ADD_KEY_1, key.getResource()));
              }
          }
          // If != null the key is already in the cache, so we just do nothing
      }