code: public byte[] get(WmsRequest request) {
          synchronized (this) {
              log.info("cache size=" + cache.size());
              return cache.get(getKey(request));
          }
      }
docs: Get the bytes of the image returned by a {@link WmsRequest}. Returns null
  if no corresponding image exists in the cache.
  
  @param request
  the WMS http request
  @return bytes of the image