call Google ads api(GoogleAdsServiceClient.mutate) exception

[ran liu]

we call the Google ads api(GoogleAdsServiceClient.mutate) ,meet  an error, the requestid is : 3VgRMsmMaXlYlZmRQLLw7A
The details are as follows:
{
"extractError": [{
"errorCode": "asset_group_listing_group_filter_error: UNIT_CANNOT_HAVE_CHILDREN",
"errorValue": "int64_value: 6462030945"
}],
"originalError": "errors {  error_code {    asset_group_listing_group_filter_error: UNIT_CANNOT_HAVE_CHILDREN  }  message: "Listing Group UNIT node cannot have children."  trigger {    int64_value: 6462030945  }  location {    field_path_elements {      field_name: "mutate_operations"      index: 0    }    field_path_elements {      field_name: "asset_group_listing_group_filter_operation"    }    field_path_elements {      field_name: "create"    }    field_path_elements {      field_name: "type"    }  }}request_id: "3VgRMsmMaXlYlZmRQLLw7A"io.grpc.StatusRuntimeException: INVALID_ARGUMENT: Request contains an invalid argument."
}