Keycloak "there was no code" after authentication with a custom OpenID Provider - keycloak

Question

I followed a quickstart called "app-profile-jee-vanilla" to add an application to a Keycloak server. After that, I enabled log in with Google. So far, so good.
Now, I wanted to add a custom OpenID provider. I developed the openid provider (still, work in progress.. I need to add all error responses still), however, when the flow finishes with success, the user is redirected to Keycloak's login page, instead of going to Vanilla authenticated. "Vanilla" logs say:
10:48:18,845 DEBUG [io.undertow.request] (default I/O-1) Matched prefix path /vanilla for path /vanilla/profile.jsp
10:48:18,847 DEBUG [org.keycloak.adapters.PreAuthActionsHandler] (default task-57) adminRequest https://localhost:8443/vanilla/profile.jsp
10:48:18,848 DEBUG [io.undertow.request.security] (default task-57) Security constraints for request /vanilla/profile.jsp are [SingleConstraintMatch{emptyRoleSemantic=AUTHENTICATE, requiredRoles=[]}]
10:48:18,848 DEBUG [io.undertow.request.security] (default task-57) Authenticating required for request HttpServerExchange{ GET /vanilla/profile.jsp request {accept=[text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8], accept-language=[en-GB,en-US;q=0.9,en;q=0.8], cache-control=[max-age=0], accept-encoding=[gzip, deflate, br], dnt=[1], user-agent=[Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36], cookie=[JSESSIONID=Cqd-3jIqTC4Mpszlilw-0HxgAEFyKLZ6i49X7irA.id3698, JSESSIONID=6B32E6C903620A3ACCB305C764A239AE], referer=[https://localhost:8444/Login.jsp?scope=openid&state=wjLUKD-74VoKSIxMNrGgxfsfk2iT7PkELy3RWoB9tg4.0dafd6d9-6253-4356-88fa-29d565dcbc49&response_type=code&client_id=this-is-a-client-id&redirect_uri=https%3A%2F%2Flocalhost%3A8543%2Fauth%2Frealms%2Fdemo%2Fbroker%2Fcustom-oidc%2Fendpoint], upgrade-insecure-requests=[1], Host=[localhost:8443]} response {X-Powered-By=[Undertow/1], Server=[WildFly/10]}}
10:48:18,849 DEBUG [io.undertow.request.security] (default task-57) Setting authentication required for exchange HttpServerExchange{ GET /vanilla/profile.jsp request {accept=[text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8], accept-language=[en-GB,en-US;q=0.9,en;q=0.8], cache-control=[max-age=0], accept-encoding=[gzip, deflate, br], dnt=[1], user-agent=[Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36], cookie=[JSESSIONID=Cqd-3jIqTC4Mpszlilw-0HxgAEFyKLZ6i49X7irA.id3698, JSESSIONID=6B32E6C903620A3ACCB305C764A239AE], referer=[https://localhost:8444/Login.jsp?scope=openid&state=wjLUKD-74VoKSIxMNrGgxfsfk2iT7PkELy3RWoB9tg4.0dafd6d9-6253-4356-88fa-29d565dcbc49&response_type=code&client_id=this-is-a-client-id&redirect_uri=https%3A%2F%2Flocalhost%3A8543%2Fauth%2Frealms%2Fdemo%2Fbroker%2Fcustom-oidc%2Fendpoint], upgrade-insecure-requests=[1], Host=[localhost:8443]} response {X-Powered-By=[Undertow/1], Server=[WildFly/10]}}
10:48:18,851 DEBUG [org.keycloak.adapters.elytron.KeycloakHttpServerAuthenticationMechanismFactory] (default task-57) Evaluating request for path [https://localhost:8443/vanilla/profile.jsp]
10:48:18,852 DEBUG [org.keycloak.adapters.PreAuthActionsHandler] (default task-57) adminRequest https://localhost:8443/vanilla/profile.jsp
10:48:18,861 DEBUG [org.keycloak.adapters.elytron.ElytronSessionTokenStore] (default task-57) Account was not in session, returning null
10:48:18,861 DEBUG [org.keycloak.adapters.OAuthRequestAuthenticator] (default task-57) there was no code
10:48:18,861 DEBUG [org.keycloak.adapters.OAuthRequestAuthenticator] (default task-57) redirecting to auth server
10:48:18,862 DEBUG [org.keycloak.adapters.OAuthRequestAuthenticator] (default task-57) callback uri: https://localhost:8443/vanilla/profile.jsp
10:48:18,863 DEBUG [org.keycloak.adapters.OAuthRequestAuthenticator] (default task-57) Sending redirect to login page: https://localhost:8543/auth/realms/demo/protocol/openid-connect/auth?response_type=code&client_id=vanilla&redirect_uri=https%3A%2F%2Flocalhost%3A8443%2Fvanilla%2Fprofile.jsp&state=65f979c1-e062-4e71-9c14-f350c5189b16&login=true&scope=openid
Keycloak logs say:
10:48:14,533 DEBUG [org.keycloak.services.resources.IdentityBrokerService] (default task-19) Got authorization code from client [vanilla].
10:48:14,549 DEBUG [org.keycloak.services.resources.IdentityBrokerService] (default task-19) Authorization code is valid.
...
10:48:14,750 DEBUG [org.keycloak.events] (default task-21) type=LOGIN, realmId=demo, clientId=vanilla, userId=b87b0a03-2418-4274-af4a-34dec666d376, ipAddress=127.0.0.1, auth_method=broker, identity_provider=custom-oidc, response_type=code, redirect_uri=https://localhost:8443/vanilla/profile.jsp, consent=persistent_consent, identity_provider_identity=tentativa123oiu123oiu, code_id=0dafd6d9-6253-4356-88fa-29d565dcbc49, username=tentativa123oiu123oiu, response_mode=query
10:48:14,751 DEBUG [org.keycloak.services.managers.AuthenticationManager] (default task-21) Removing old user session: session: 553c5ae6-c713-4009-96c3-d7cd5798f702
10:48:14,761 DEBUG [org.keycloak.services.managers.AuthenticationManager] (default task-21) Create login cookie - name: KEYCLOAK_IDENTITY, path: /auth/realms/demo, max-age: -1
...
10:48:15,505 DEBUG [org.keycloak.authentication.AuthenticationProcessor] (default task-18) AUTHENTICATE CLIENT
10:48:15,512 DEBUG [org.keycloak.authentication.ClientAuthenticationFlow] (default task-18) client authenticator: client-secret
10:48:15,513 DEBUG [org.keycloak.authentication.ClientAuthenticationFlow] (default task-18) client authenticator SUCCESS: client-secret
10:48:15,513 DEBUG [org.keycloak.authentication.ClientAuthenticationFlow] (default task-18) Client vanilla authenticated by client-secret
10:48:15,514 DEBUG [org.keycloak.protocol.oidc.endpoints.TokenEndpoint] (default task-18) Adapter Session 'Cqd-3jIqTC4Mpszlilw-0HxgAEFyKLZ6i49X7irA' saved in ClientSession for client 'vanilla'. Host is 'id3698'
10:48:15,650 DEBUG [org.keycloak.events] (default task-18) type=CODE_TO_TOKEN, realmId=demo, clientId=vanilla, userId=b87b0a03-2418-4274-af4a-34dec666d376, ipAddress=127.0.0.1, client_session_host=id3698, token_id=834c1b6f-9692-453b-94ee-604db2a1ffc4, grant_type=authorization_code, refresh_token_type=Refresh, client_session_state=Cqd-3jIqTC4Mpszlilw-0HxgAEFyKLZ6i49X7irA, refresh_token_id=b8d8ba7c-3a0c-4012-9cdb-ab99d6ccaa11, code_id=0dafd6d9-6253-4356-88fa-29d565dcbc49, client_auth_method=client-secret
In Keycloak, I tried to turn on the Cookie authentication flow. When I do this, after logging in, the browser just enters a redirect loop.
Does anyone have any idea of what might be wrong here? What am I missing?