public void populateAnnotation(Varnode vn) {
		Address addr = vn.getAddress();
		if (!addr.isLoadedMemoryAddress() || addrMappedSymbols.containsKey(addr)) {
			return;
		}
		Symbol symbol = symbolTable.getPrimarySymbol(addr);
		if (symbol == null) {
			return;
		}
		HighSymbol highSym;
		if (symbol instanceof CodeSymbol) {
			highSym = new HighCodeSymbol((CodeSymbol) symbol, func);
		}
		else if (symbol instanceof FunctionSymbol) {
			highSym = new HighFunctionShellSymbol(symbol.getID(), symbol.getName(),
				symbol.getAddress(), func.getDataTypeManager());
		}
		else {
			return;
		}
		insertSymbol(highSym, symbol.getAddress());
	}
Some Varnode annotations refer to global symbols.  Check if there is symbol at the
Varnode address and, if there is, create a corresponding HighSymbol
@param vn is the annotation Varnode
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/pcode/GlobalSymbolMap.java