public boolean isThunk(long key) {
		lock.acquire();
		try {
			FunctionDB function = cache.get(key);
			if (function != null) {
				return function.isThunk();
			}
			try {
				return thunkAdapter.getThunkRecord(key) != null;
			}
			catch (IOException e) {
				dbError(e);
			}
			return false;
		}
		finally {
			lock.release();
		}
	}
Remove variable references in the given address set.
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/function/FunctionManagerDB.java