code: public static Http2Exception getEmbeddedHttp2Exception(Throwable cause) {
          while (cause != null) {
              if (cause instanceof Http2Exception) {
                  return (Http2Exception) cause;
              }
              cause = cause.getCause();
          }
          return null;
      }
docs: Iteratively looks through the causality chain for the given exception and returns the first
  {@link Http2Exception} or {@code null} if none.