@Test
void context() {

    var channel = new ChannelImpl<TestWebSocketMessage, TestWebSocketMessage>(null, null, null);
    channel.context().put("k1", "v1");
    assertThat(channel.context().get("k1")).isEqualTo("v1");
    channel.context().put("k1", null);
    assertThat(channel.context().get("k1")).isNull();
}