def METHOD_NAME(cls) -> dict[str, str]:
    """Validate the value of ``hybrid_mapping`` attribute."""
    mapping = json.loads(os.environ.get("CN_HYBRID_MAPPING", "{}"))
    # build whitelisted mapping based on supported PERSISTENCE_DATA_KEYS and PERSISTENCE_TYPES
    try:
        sanitized_mapping = {
            key: type_ for key, type_ in mapping.items()
            if key in PERSISTENCE_DATA_KEYS and type_ in PERSISTENCE_TYPES
        }
    except AttributeError:
        # likely not a dict
        raise ValueError(f"Invalid hybrid mapping {mapping}")
    if sorted(sanitized_mapping.keys()) != sorted(PERSISTENCE_DATA_KEYS):
        raise ValueError(f"Missing key(s) in hybrid mapping {mapping}")
    return sanitized_mapping