docs: private void validateStatusLine(StatusLine statusLine, Map<String, List<String>> headers, WebSocketInputStream input) throws WebSocketException
      {
          // If the status code is 101 (Switching Protocols).
          if (statusLine.getStatusCode() == 101)
          {
              // OK. The server can speak the WebSocket protocol.
              return;
          }
  
          // Read the response body.
          byte[] body = readBody(headers, input);
  
          // The status code of the opening handshake response is not Switching Protocols.
          throw new OpeningHandshakeException(
              WebSocketError.NOT_SWITCHING_PROTOCOLS,
              "The status code of the opening handshake response is not '101 Switching Protocols'. The status line is: " + statusLine,
              statusLine, headers, body);
      }