code: protected B server(boolean isServer) {
          enforceConstraint("server", "connection", connection);
          enforceConstraint("server", "codec", decoder);
          enforceConstraint("server", "codec", encoder);
  
          this.isServer = isServer;
          return self();
      }
docs: Sets if {@link #build()} will to create a {@link Http2Connection} in server mode ({@code true})
  or client mode ({@code false}).