def _create_evg_build_variant_map(expansions_file_data):
    """
    Generate relationship of base buildvariant to generated buildvariant.

    :param expansions_file_data: Config data file to use.
    :return: Map of base buildvariants to their generated buildvariants.
    """
    burn_in_tag_build_variants = expansions_file_data["burn_in_tag_buildvariants"]

    if burn_in_tag_build_variants:
        return {
            base_variant: f"{base_variant}-required"
            for base_variant in burn_in_tag_build_variants.split(" ")
        }

    return {}