Codegen silently skips some getters

Given data object:

```
@DataObject(generateConverter=true)
public class MyDo {
private Map> data;
... JsonObject ctor, toJson, getter/setter
}
```

The converter generated for it silently skips the `Map> getData()` method conversion, does not throw errors during build.

To me, this did not occur at all when service (that defines API using MyDo) used locally, all worked just fine. But once used remotely (via ProxyHelper.registerService), things suddenly broke naturally, as data was simply missing when sent over wire.

Is this intentional? As I got really puzzled where the data goes away?

首先跟踪 MyDo.getData() getter 的转换器生成过程，并复现 issue 中描述的嵌套 Map> 情况。将本地调用与通过 ProxyHelper.registerService 的远程路径进行比较，并确定缺失字段是有意的限制还是转换 bug；完成的标准是记录该行为，或使 getter 得到一致的转换。

由索引模型根据 Issue 内容生成。