code.aload().setParam(0);
code.checkcast().setType(Map.class);
code.invokevirtual().setMethod(type, "putAll", void.class,
new Class[] { Map.class });
}
code.areturn();
code.calculateMaxStack();
code.calculateMaxLocals();
// key type
BCField keyType = bc.declareField("keyType", Class.class);