In order to correctly handle QName prefix resolution I have added DMNModelInstrumentedBase.getPrefixForNamespaceURI(..) to the UI model. I will add support for setting it appropriately as the User authors a DMN model in the UI (i.e. to new elements as and when created) however the marshaller will need to set it accordingly when going from KIE-DMN-model to UI-DMN-model too; so existing diagrams have the parental hierarchy correctly set.

This depends on https://github.com/kiegroup/kie-wb-common/pull/1818 being merged.