Allow custom claims to be something other than a string

[raysuelzer]

There are cases where a claim value will be an object. Consider the following use case:

A custom claims object is added for {response.content}
{response.content}

This content is a JSON object of claims that is retrieved from another service. Currently, this will be treated as a string instead of being nested as JSON.

There are multiple ways to solve this, but I wanted to point out that this is a pretty significant shortfall of the service.