private static void makeDefaultBody(Bytecode b, CtClass type) {
        int op;
        int value;
        if (type instanceof CtPrimitiveType) {
            CtPrimitiveType pt = (CtPrimitiveType)type;
            op = pt.getReturnOp();
            if (op == Opcode.DRETURN)
                value = Opcode.DCONST_0;
            else if (op == Opcode.FRETURN)
                value = Opcode.FCONST_0;
            else if (op == Opcode.LRETURN)
                value = Opcode.LCONST_0;
            else if (op == Opcode.RETURN)
                value = Opcode.NOP;
            else
                value = Opcode.ICONST_0;
        }
        else {
            op = Opcode.ARETURN;
            value = Opcode.ACONST_NULL;
        }

        if (value != Opcode.NOP)
            b.addOpcode(value);

        b.addOpcode(op);
    }