@Override
    public Iterator<Map.Entry<String, Object>> getIterator() {
        return variables.getIterator();
    }
@Test
    public void testGetIteratorIsUnmodifable() {
        Iterator<Map.Entry<String, Object>> iterator = unmodifiables.getIterator();
        assertThat(iterator.hasNext(), CoreMatchers.is(true));
        iterator.next();
        assertThrowsUnsupportedOperation(iterator::remove);
    }