Serve all core schemas on /Schemas endpoint

[hrenard]

Hi @di-wu,

Another one ! I'm still trying to test a Keycloak SCIM Client, and it complains about missing schemas. So this pull adds all core schemas ont the /Schemas endpoint. It relates to RFC7644 Section 4.
I'm not sure to understand if it's required, optional or bad. What do you think ?

[q-uint]

I am reluctant to add the schemas of Schema, ResourceType and ServiceProviderConfig because of the following reasons:

• They are related to the protocol/specification, not the implementation.
• The schemas are the same everywhere, so they do not disclose any additional information.

[hrenard]

I find the RFC not clear about this.
You're right those schemas are the sames everywhere, then so is User and Group. And it's likely clients don't call them at all. But there is no official URL for these schemas. I would expect core schemas to be either available publicly or by the service provider.

I guess it's not a big deal, and it probably will serve few or zero person. But would it be worth to add it behind a server option ?

[richard-rance]

There are a few active RFCs before the IETF that would see new attributes added to the top level of ServiceProviderConfig. I think it would be reasonable to expose these schemas so that it is clear what the server is aware of.