All fields are merged in case of related entity with the same iri

In case of subresources using the same "iri" of the parent, all fields are merged into the same resource.

Test case, two entities with the same iri:

```
// entities
User:
id
username
password
userProfile (OneToOne)

UserProfile:
id
photo
firstname
...
```

```yaml
// resources file
App\Entity\User:
iri: 'http://schema.org/Person'

App\Entity\UserProfile:
iri: 'http://schema.org/Person'
```

Result is all the fields **of the latest entity (with the same iri) parsed** by the `parseHydraDocumentation()`, in my case the fields are from "UserProfile" entity.