deserializeArray returns undefined when called on an empty array

Hi, is this intended behavior?
```
  class Example {
      hello = null;
      world = null;
    }
    const helloJson = []
    const result = ObjectMapper.deserializeArray(Order, helloJson);

    // expected []
    // was undefined
    console.log(result);

```
If not, it should be fixed. If so, it should be documented, as it seems like it could cause confusion.