private boolean shouldBeValidFunction(Program program, Instruction targetInstr) {
		Function func =
			program.getFunctionManager().getFunctionContaining(targetInstr.getMinAddress());
		if (func != null) {
			return false;
		}
		ReferenceIterator refs =
			program.getReferenceManager().getReferencesTo(targetInstr.getMinAddress());
		while (refs.hasNext()) {
			Reference ref = refs.next();
			RefType refType = ref.getReferenceType();
			if (refType.isFlow()) {
				return false;
			}
			if (refType.isRead() || refType.isWrite()) {
				return false;
			}
		}
		return true;
	}
Check for any jumps to Externals (manufactured labels).
Any externals directly jumped to should be looked at as a call.

Note: this shouldn't affect jumps in thunks, but beware...
@param monitor
@throws CancelledException
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/analysis/OperandReferenceAnalyzer.java