Since we have demonstrated usefulness of QueryExpressions in single-data setting, expose evaluations of these through QueryOperations, which can be implemented by ReadTransaction et al.

Since query evaluation can be performed on DOM data, we can provide the capability out of the box in mdsal-binding-dom-adapter, again using DOMQueryEvaluator. This will work with any transaction provider, riding on top of the read() operation.

For mdsal-binding-util we just retrofit ReadTransaction with a delegating implementation. If the backend does not support queries they will just throw UnsupportedOperationException.