@Override
    public void addDocument(SDDocumentType docType) {
        if (getName() == null) {
            setName(docType.getName());
        }
        super.addDocument(docType);
    }
A search that was derived from an sd file containing no search element(s), only
document specifications, so the name of this is decided by parsing and adding the document instance.

@author vegardh
config-model/src/main/java/com/yahoo/schema/DocumentOnlySchema.java