Add support for configuring sslContext in StandardWebSocketClient

[wolf-itc]

Currently StandardWebSocketClient supports SSL using user properties:
standardWebSocketClient.setUserProperties(Map.of(Constants.SSL_CONTEXT_PROPERTY, sslContext));

Unfortunately this support ends with Tomcat 11. New way to go:
ClientEndpointConfig endpointConfig = ClientEndpointConfig.Builder.create().sslContext(sslContext).build();

But the creation of ClientEndpointConfig is capsulated in the class StandardWebSocketClient, so sslContext(...) can not be inserted there. Would it be possible to enable that?

[snicoll]

That looks reasonable to me. Would moving createEndpointConfig to a protected method do the trick for you?

[wolf-itc]

Hi Stéphane,
thank you for taking the time to look at this!
Yes, I think this should work.
Best regards
Martin

[jhoeller]

While for the reactive StandardWebSocketClient, I've turned createEndpointConfig to a protected method indeed (in line with some other protected methods there), I went with direct SSLContext support in the form of a setSslContext method on the regular StandardWebSocketClient (along the lines of the existing user properties support there).