TypedAggregation.project incorrect conversion

```java
public class A {

    @Id
    @Field
    private String id;

}
```
Get when using`TypedAggregation.project(A.class)`
```
{
    "$project": {
        "_id": "1"
    }
}
```
The correct result should be
```
{
    "$project": {
        "_id": 1
    }
}
```

#### spring-data-mongodb version: 3.1.2