default boolean isValid() {

        // A user context is always valid unless explicitly updated by an
        // implementation
        return true;

    }
Returns true if the session for the User associated with this user
context is valid, or false otherwise. If the session is not valid,
the webapp can be expected to terminate the session within a short
period of time.

NOTE: The webapp currently checks once a minute, and terminates any
session marked as invalid.

@return
    true if the session for the User associated with this user
    context is valid, or false otherwise.
guacamole-ext/src/main/java/org/apache/guacamole/net/auth/UserContext.java