Behind Proxies that make headers lowercase fails

[philjones88]

Behind Istio that makes all HTTP headers it proxies to applications lowercase, this code here fails, it is using a HashMap and as a result is case sensitive.

https://github.com/usnistgov/jsip/blob/master/src/gov/nist/javax/sip/stack/WebSocketHttpHandshake.java#L114

Fails as it's looking for Sec-WebSocket-Key but the headers HashMap would have sec-websocket-key.

For example:

var test = new HashMap<String, String>();
test.put("sec-lower", "foo");
test.put("Sec-Upper", "bar");
System.out.println("Test: " + test.get("sec-upper"));
System.out.println("Test: " + test.get("sec-lower"));

Outputs:

Test: null
Test: foo

Interestingly other parts of the code seem to be case insensitively written, e.g.

https://github.com/usnistgov/jsip/blob/master/src/gov/nist/javax/sip/stack/WebSocketHttpHandshake.java#L85

So behind Istio or other proxies that lowercase headers the response Sec-WebSocket-Accept header is always of the value of the string null