def METHOD_NAME(
    cls, value: List[ManualWebhookField]
) -> List[ManualWebhookField]:
    """
    Verify that pii_fields and dsr_package_labels are unique.
    Set the dsr_package_label to a snake_cased lower case version of pii field if it doesn't exist.
    """
    unique_pii_fields: Set[str] = {field.pii_field for field in value}
    if len(value) != len(unique_pii_fields):
        raise ValueError("pii_fields must be unique")
    for field in value:
        if not field.dsr_package_label:
            field.dsr_package_label = DSRLabelFieldType(
                to_snake_case(field.pii_field)
            )
    unique_dsr_package_labels: Set[Optional[str]] = {
        field.dsr_package_label for field in value
    }
    if len(value) != len(unique_dsr_package_labels):
        # Postponing dsr_package_label uniqueness check in case we get overlaps
        # above when we fallback to converting pii_fields to dsr_package_labels
        raise ValueError("dsr_package_labels must be unique")
    return value