Deserialisation doesn't work with translated attribution

[cmahnke]

See this manifest:

"attribution" : {
        "de" : [
            "Georg-August Universität Göttingen"
        ],
        "en" : [
            "Goobi viewer"
        ]
    }

The IiifObjectMapper fails with:

com.fasterxml.jackson.databind.JsonMappingException: (was java.lang.NullPointerException) (through reference chain: de.digitalcollections.iiif.model.sharedcanvas.Manifest["attribution"])

This certainly related to different minor versions of the IIIF Presentation API 2.x.

[cmahnke]

It seem's that the manifest is wrong, see. I'm currently asking our vendor for clarification...