code: static void setHttp2Authority(String authority, Http2Headers out) {
          // The authority MUST NOT include the deprecated "userinfo" subcomponent
          if (authority != null) {
              if (authority.isEmpty()) {
                  out.authority(EMPTY_STRING);
              } else {
                  int start = authority.indexOf('@') + 1;
                  int length = authority.length() - start;
                  if (length == 0) {
                      throw new IllegalArgumentException("authority: " + authority);
                  }
                  out.authority(new AsciiString(authority, start, length));
              }
          }
      }
docs: package-private for testing only