Deserializing nested xml within json

Is there a way to somehow deserialize nested xml witout custom deserializer?. We have some huge json which has a field which actually contains text with xml, so we would like to just mark it some annotation to point jackson that it's should be deserialized by another way. Seems like default implementation tries to invoke a constructor with String argument on an object that should be deserialized. The way we use is custom deserializer for a json field which contains that text and then we use default XmlMapper.
That's some kind of what we need to deserialize:
`{
"metadata": "some difficult XML data is here"
}`