endpoint WebSocketClient
{
    // Connection API
    Connected(i32 connection_id) =|
    Received(i32 connection_id, bool is_text, ByteBuffer data) =|
    Errored(i32 connection_id, i32 message) =|
    Closed(i32 connection_id, u16 code, String reason, bool clean) =|

    // Certificate requests
    CertificateRequested(i32 connection_id) =|
}