The %OAuth2.Server.Validate class is the default ValidateUserClass which is included with the server.
The default class will use the user database of the Cache instance where the authorization server
is located to validate the user. The supported properties will be
issuer (Issuer), roles and sub (Username).
The ValidateUserClass is specified in the Authorization Server Configuration. It must contain a ValidateUser method which will validate a username/password combination and return a set of properties associated with this user.
The SupportedClaims method returns a $list of claims that are supported by this authorization server based on customizations. The SupportedClaims method is in the ValidateUserClass since this is where additional claims are usually added. The returned list is added to the list of claims defined by OpenID Connect Core and should include JWT, IDToken, userinfo endpoint and introspection endpoint claims.
The ValidateClient method returns true (1), if the client_id and client_secret refer to a client computer which may use the client credentials grant type based on whatever criteria the method chooses to implement. This client will already have been verified to be registered to this authorization server and thus will usually be accepted. ValidateClient populates the properties array argument with any properties needed to generate the access token. This correspond to the Properties arguments of OAuth2.Server.Token. The authorization server will always add the "iss" (URL of authorization server), "sub" (client_id), and "exp" (expiration time in seconds since December 31st, 1840) to ClaimValues and "client_id" (client_id of the requesting client) to CusotmProperties after return from ValidateUser if they have not already been added.
If not valid then false is returned.
This default ValidateClient accepts all clients and adds no properties.
Your custom ValidateUser method must return true (1) only if the username and password refer to a valid user based on whatever criteria you choose to implement. It must return false in other cases.
If password="", then the user is already logged into an existing session and the password does not need to be validated.
In addition, this method receives the properties array and can further modify it; this correspond to the Properties property of %OAuth2.Server.Token. The authorization server will always add the "iss" (URL of authorization server), "sub" (client_id), and "exp" (expiration time in seconds since December 31st, 1840) to ClaimValues and "client_id" (client_id of the requesting client) to CusotmProperties after return from ValidateUser if they have not already been added.
This sample ValidateUser method validates the user based on the Cache users for this instance.