stringImplicitlyUnwrapped 未解包问题

文档中提到：
```
var stringImplicitlyUnwrapped: String!
```
这里支持解包的方式，但是我实际使用中，使用一样的方式：
但是，在print出来的时候：
```
task_name: Optional("前端开发")
```
而不是
```
task_name: "前端开发"
```

No source file or test is named. Reproduce the HandyJSON case with a Swift String! property and compare the printed Optional value with the documented behavior; identify whether the discrepancy is in deserialization or printing, then add a regression test that captures the expected result.

Written by the indexing model from the issue text.