code: public static void setUnsupported(SocketAddress remoteAddress, SessionProtocol protocol) {
          final String key = key(remoteAddress);
          final CacheEntry e = getOrCreate(key);
  
          if (e.addUnsupported(protocol)) {
              logger.debug("Updated: '{}' does not support {}", key, e);
          }
      }
docs: Updates the cache with the information that the specified {@code remoteAddress} does not support
  the specified {@link SessionProtocol}.