grouping augments fail to generate code

The following snippet does not result in augmented Tlvs.java being generated:

typedef of-id {
type uint16;
}

typedef of-id {
type uint16;
}

grouping object-header {
leaf processing-rule

{ type boolean; default false; }

leaf ignore { type boolean; default false; }

}

grouping object {
uses object-header;

container tlvs {

}
}

grouping open-object {
uses object {
augment "tlvs" {
container of-list

{ uses of-list-tlv; }

}
}
}