public boolean isSkeleton() {
        return (getModel().getEntityID() == null);
    }
Returns true if this user is a skeleton user, lacking a database entity
entry.

@return 
    True if this user is a skeleton user, otherwise false.
extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-base/src/main/java/org/apache/guacamole/auth/jdbc/user/ModeledUser.java