Major Description
Right now for the OAuth 2.0 data provider, we can issue access tokens in JWT format by specifying the "useJwtFormatForAccessTokens" property. However this persists the encoded JWT token, something that is problematic with the JPA provider as the Id column of the AccessToken class can't handle the size of the token.
I propose to add a new property called "persistJwtEncoding" to be used in conjunction with "useJwtFormatForAccessTokens". By default "persistJwtEncoding" is true for backwards compatibility reasons.
When "persistJwtEncoding" is false, then the AccessToken that is persisted just contains the Id (opaque String) as for the non-useJwtFormatForAccessTokens case. However, the JWT-encoded access token is returned to the client.
For the AbstractAccessTokenValidator and the TokenIntrospectionService, we can also set "persistJwtEncoding" to false to validate and parse the received token into a JWTToken. The Id is then extracted from the token and used to retrieve the access token from storage.