To verify the access tokens that a authorization server issues, the access token validator uses HTTP to submit the tokens to server's token introspection endpoint.
Before using a access token validator, create a client that represents the access token validator in the configuration. This client must use the Access Token Validation grant type.
This step allows the authorization server to determine whether a token is valid.
Access tokens issued using the OAuth 2 client credentials grant type are issued directly to a client and do not contain a subject. Such tokens cannot be accepted by the directory server.
Because this step requires an outgoing HTTP request to the authorization server, the access token validator might perform slower than other access token validator types. The validation result is guaranteed to be current, which is an important consideration if the authorization server permits the revocation of access tokens.