public List<DecoratedUserContext> getUserContexts(String authToken)
            throws GuacamoleException {
        return getGuacamoleSession(authToken).getUserContexts();
    }
Returns all UserContexts associated with a given auth token, if the auth
token represents a currently logged in user. Throws an unauthorized
error otherwise.

@param authToken
    The auth token to check against the map of logged in users.

@return
    A List of all UserContexts associated with the provided auth token.

@throws GuacamoleException
    If the auth token does not correspond to any logged in user.
guacamole/src/main/java/org/apache/guacamole/rest/auth/AuthenticationService.java