@Override
	default ExternalReference getExternalReference(int opIndex) {
		return null;
	}
A base interface for implementations of {@link TraceCodeUnit}

<p>
This behaves somewhat like a mixin, allowing it to be used on code units as well as data
components, e.g., fields of a struct data unit.
Ghidra/Debug/Framework-TraceModeling/src/main/java/ghidra/trace/database/listing/DBTraceCodeUnitAdapter.java