verify(customTree).close();
    }

    /**
     * Custom SmbTree interface for testing unwrap functionality.
     */
    interface CustomSmbTree extends SmbTree {
        void customMethod();
    }

    /**
     * Extended SmbTree interface for testing nested unwrapping.
     */
    interface ExtendedSmbTree extends SmbTree {
        void extendedMethod();
    }

    /**