@Override
	public UndefinedDBTraceData getContaining(long snap, Address address) {
		return getAt(snap, address); // Undefined all of size 1
	}
Get an address set view for optimizing various queries

<p>
As its code may suggest, this creates the lazy address set view {@code all - definedUnits},
and wraps it in a cached address set view.

@param snap the snapshot key for the address set
@return the address set
Ghidra/Debug/Framework-TraceModeling/src/main/java/ghidra/trace/database/listing/DBTraceUndefinedDataView.java