@Override
	public ExternalReference getExternalReference(int opIndex) {
		if (refMgr == null)
			return null;
		Reference[] refs = refMgr.getReferencesFrom(address, opIndex);
		for (Reference element : refs) {
			if (element.isExternalReference()) {
				return (ExternalReference) element;
			}
		}
		return null;
	}
Get ALL reference FROM this code unit.
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/app/util/PseudoCodeUnit.java