def METHOD_NAME(data: Dict[str, Any], key: str) -> str:
    existing = data.get(key, {})
    if not existing:
        # Manage every resource possible
        return ".*"
    # Exclude existing resources from managed resources
    LOG.info(
        "Found existing {} in community config: {}".format(
            key, ", ".join(existing)
        )
    )
    return "(?!({})$)".format("|".join(existing))