Custom schema's on APIView classes are not picked up by the schema generation.

[joeribekker]

• DRF OpenAPI version: 1.3
• Python version: 3.6

Description

Custom schema's on APIView classes are not picked up by the schema generation.

What I Did

class UserViewSet(viewsets.ModelViewSet):
    queryset = User.objects.all()
    serializer_class = UserSerializer

    schema = AutoSchema(
        manual_fields=[
            coreapi.Field('fields', description='Which field(s) to show.'),
        ]
    )

The UserViewSet.schema is not picked up by the documentation. You would expect to have it show the "fields" parameter.