get modified properties

def _get_instance_changes(current, state):
    '''
    get modified properties
    '''
    # get keys
    current_keys = set(current.keys())
    state_keys = set(state.keys())

    # compare configs
    changed = salt.utils.data.compare_dicts(current, state)
    for change in salt.utils.data.compare_dicts(current, state):
        if change in changed and changed[change]['old'] == "":
            del changed[change]
        if change in changed and changed[change]['new'] == "":
            del changed[change]

    return changed