code: static boolean isEndToEnd(String fieldName) {
      return !"Connection".equalsIgnoreCase(fieldName)
          && !"Keep-Alive".equalsIgnoreCase(fieldName)
          && !"Proxy-Authenticate".equalsIgnoreCase(fieldName)
          && !"Proxy-Authorization".equalsIgnoreCase(fieldName)
          && !"TE".equalsIgnoreCase(fieldName)
          && !"Trailers".equalsIgnoreCase(fieldName)
          && !"Transfer-Encoding".equalsIgnoreCase(fieldName)
          && !"Upgrade".equalsIgnoreCase(fieldName);
    }
docs: Returns true if {@code fieldName} is an end-to-end HTTP header, as defined by RFC 2616,
  13.5.1.