HttpSessionStrategy getRequestedSessionId->getRequestedSessionIds

[rwinch]

Previously HttpSessionStrategy contained a flaw in that it only allowed resolving a single session id. However, it is common for multiple session ids to be present in the request. For example, when using cookies the same cookie name may be present for multiple domains or multiple paths.

This commit changes HttpSessionStrategy from:

String getRequestedSessionId();

to

List<String> getRequestedSessionIds();

This means that implementations of HttpSessionStrategy should change from
something like:

public String getRequestedSessionId() {
   ...
   return result;
}

to

public List<String> getRequestedSessionIds() {
    ...
    return result == null ? 
        Collections.<String>emptyList() : Collections.singleton(result);
}