A common transformer pattern for newly added attributes is to discard the attribute if the value is the default value, and reject if otherwise defined.

e.g.

builder.getAttributeBuilder()
    .setDiscard(new DiscardAttributeChecker.DiscardAttributeValueChecker(ATTRIBUTE.getDefaultValue()), ATTRIBUTE);
    .addRejectCheck(RejectAttributeChecker.DEFINED)
    ;

This common implementation can be implemented more concisely, such that a single instance can be used for any attribute.