Only one resource per type is auto included

I have the following content type:
field_image -> reference to a media image (media--image is the resource name)
field_tag -> reference to a taxonomy term which has a field_image reference to a media image

The image referenced by the taxonomy term is not included because the $visited array in getIncludes() already has a resource of type media--image.

We should probably create $key from both the $prefix and $resource_type->getTypeName() for better unicity.