def property_mapping_to_dict(cs_data):
    """Converts the property mapping in config strategy data from an
       array like [ {'source': 'string'}, {'target': 'string'} ] to
       a dict with { 'source-string': 'target-string', ... }.
    """

    property_mapping_arr = cs_data['properties']['mapping']

    property_mapping = {}
    for mapping_obj in property_mapping_arr:
        source = mapping_obj['source']
        target = mapping_obj['target']

        if source in property_mapping:
            property_mapping[source].append(target)
        else:
            property_mapping[source] = [target]

    return property_mapping