Delegate from one custom type handler to another.

Let's say I have a value object (to avoid primitive obsession) and I want to create a custom type handler that internally just delegates to the appropriate type handler for the type backing my value object (e.g., treat record Username(string Value) as string, and make its type handler simply take Value and handle that instead using whichever type handler exists for a string type).

I considered the possibility of using SqlMapper.LookupDbType, but that's deprecated, and documentation says it's for internal use only. Are there any safe workarounds for this?

Start by reviewing the custom type-handler behavior described in the issue and the referenced SqlMapper.LookupDbType API and its documentation. Determine whether a supported delegation mechanism can be specified; done would be a documented safe workaround or a clearly scoped API change for handlers backing value objects.