Not able to register a custom SPI

We are in process of upgrading the Keycloak from 3.4.0 to 15.0.2
After upgrading the Keycloak the server is not registering the AccessTokenIntrospectProviderFactory however it is loading the other factory classes like AutoLinkIdpLoginAuthenticatorFactory, RealmResourceProviderFactory etc…

All these files were added under META-INF.services