public DBTraceReference addShiftedReference(long creationSnap, Address from, Address to,
			int shift) {
		return trace.getReferenceManager()
				.addShiftedReference(Lifespan.nowOn(creationSnap), from, to, shift, RefType.DATA,
					SourceType.DEFAULT, -1);
	}
Add a shifted memory reference

<p>
TODO: This uses opIndex -1, which doesn't make sense for a shifted reference. The "to"
address is computed (I assume by the analyzer which places such reference) as the operand
value shifted by the given shift amount. What is the opIndex for a data unit? Probably 0,
since the "mnemonic" would be its type? Still, this suffices for testing the database.

@param creationSnap the starting snap
@param from the from address
@param to the to address
@param shift the shift
@return the reference
Ghidra/Debug/Framework-TraceModeling/src/test/java/ghidra/trace/database/ToyDBTraceBuilder.java