Extension to org.keycloak.forms.login.LoginFormsProviderFactory breaking Keycloak 17

I’m trying to port my plugins to Keycloak 17, and after adding a plugin for the LoginFormsProviderFactory keycloak starts up but it can’t open the administration console. The only exception that we have is a NullPointerException at AuthorizationEndpointBase::createAuthenticationSession while getting the LoginsFormProvider:

session.getProvider(LoginFormsProvider.class).setAuthenticationSession(authSession);

I’ve removed any external dependencies from my plugin to avoid problems with class loader.
If I remove this LoginFormsProvider plugin and leave all the others it works fine.

Follows the stacktrace:

2022-03-03 12:11:56,729 ERROR [org.keycloak.services.error.KeycloakErrorHandler] (executor-thread-0) Uncaught server error: java.lang.NullPointerException
        at org.keycloak.protocol.AuthorizationEndpointBase.createAuthenticationSession(AuthorizationEndpointBase.java:209)
        at org.keycloak.protocol.oidc.endpoints.AuthorizationEndpoint.process(AuthorizationEndpoint.java:178)
        at org.keycloak.protocol.oidc.endpoints.AuthorizationEndpoint.buildGet(AuthorizationEndpoint.java:112)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at org.jboss.resteasy.core.MethodInjectorImpl.invoke(MethodInjectorImpl.java:170)
        at org.jboss.resteasy.core.MethodInjectorImpl.invoke(MethodInjectorImpl.java:130)
        at org.jboss.resteasy.core.ResourceMethodInvoker.internalInvokeOnTarget(ResourceMethodInvoker.java:660)
        at org.jboss.resteasy.core.ResourceMethodInvoker.invokeOnTargetAfterFilter(ResourceMethodInvoker.java:524)
        at org.jboss.resteasy.core.ResourceMethodInvoker.lambda$invokeOnTarget$2(ResourceMethodInvoker.java:474)
        at org.jboss.resteasy.core.interception.jaxrs.PreMatchContainerRequestContext.filter(PreMatchContainerRequestContext.java:364)
        at org.jboss.resteasy.core.ResourceMethodInvoker.invokeOnTarget(ResourceMethodInvoker.java:476)
        at org.jboss.resteasy.core.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:434)
        at org.jboss.resteasy.core.ResourceLocatorInvoker.invokeOnTargetObject(ResourceLocatorInvoker.java:192)
        at org.jboss.resteasy.core.ResourceLocatorInvoker.invoke(ResourceLocatorInvoker.java:152)
        at org.jboss.resteasy.core.ResourceLocatorInvoker.invokeOnTargetObject(ResourceLocatorInvoker.java:183)
        at org.jboss.resteasy.core.ResourceLocatorInvoker.invoke(ResourceLocatorInvoker.java:141)
        at org.jboss.resteasy.core.ResourceLocatorInvoker.invoke(ResourceLocatorInvoker.java:32)
        at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:492)
        at org.jboss.resteasy.core.SynchronousDispatcher.lambda$invoke$4(SynchronousDispatcher.java:261)
        at org.jboss.resteasy.core.SynchronousDispatcher.lambda$preprocess$0(SynchronousDispatcher.java:161)
        at org.jboss.resteasy.core.interception.jaxrs.PreMatchContainerRequestContext.filter(PreMatchContainerRequestContext.java:364)
        at org.jboss.resteasy.core.SynchronousDispatcher.preprocess(SynchronousDispatcher.java:164)
        at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:247)
        at io.quarkus.resteasy.runtime.standalone.RequestDispatcher.service(RequestDispatcher.java:73)
        at io.quarkus.resteasy.runtime.standalone.VertxRequestHandler.dispatch(VertxRequestHandler.java:151)
        at io.quarkus.resteasy.runtime.standalone.VertxRequestHandler.handle(VertxRequestHandler.java:82)
        at io.quarkus.resteasy.runtime.standalone.VertxRequestHandler.handle(VertxRequestHandler.java:42)
        at io.vertx.ext.web.impl.RouteState.handleContext(RouteState.java:1212)
        at io.vertx.ext.web.impl.RoutingContextImplBase.iterateNext(RoutingContextImplBase.java:163)
        at io.vertx.ext.web.impl.RoutingContextImpl.next(RoutingContextImpl.java:141)
        at io.quarkus.vertx.http.runtime.StaticResourcesRecorder$2.handle(StaticResourcesRecorder.java:67)
        at io.quarkus.vertx.http.runtime.StaticResourcesRecorder$2.handle(StaticResourcesRecorder.java:55)
        at io.vertx.ext.web.impl.RouteState.handleContext(RouteState.java:1212)
        at io.vertx.ext.web.impl.RoutingContextImplBase.iterateNext(RoutingContextImplBase.java:163)
        at io.vertx.ext.web.impl.RoutingContextImpl.next(RoutingContextImpl.java:141)
        at io.quarkus.vertx.http.runtime.VertxHttpRecorder$5.handle(VertxHttpRecorder.java:362)
        at io.quarkus.vertx.http.runtime.VertxHttpRecorder$5.handle(VertxHttpRecorder.java:340)
        at io.vertx.ext.web.impl.RouteState.handleContext(RouteState.java:1212)
        at io.vertx.ext.web.impl.RoutingContextImplBase.iterateNext(RoutingContextImplBase.java:163)
        at io.vertx.ext.web.impl.RoutingContextImpl.next(RoutingContextImpl.java:141)
        at org.keycloak.quarkus.runtime.integration.web.QuarkusRequestFilter.lambda$createBlockingHandler$1(QuarkusRequestFilter.java:66)
        at io.vertx.core.impl.ContextImpl.lambda$null$0(ContextImpl.java:159)
        at io.vertx.core.impl.AbstractContext.dispatch(AbstractContext.java:100)
        at io.vertx.core.impl.ContextImpl.lambda$executeBlocking$1(ContextImpl.java:157)
        at io.quarkus.vertx.core.runtime.VertxCoreRecorder$13.runWith(VertxCoreRecorder.java:543)
        at org.jboss.threads.EnhancedQueueExecutor$Task.run(EnhancedQueueExecutor.java:2449)
        at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1478)
        at org.jboss.threads.DelegatingRunnable.run(DelegatingRunnable.java:29)
        at org.jboss.threads.ThreadLocalResettingRunnable.run(ThreadLocalResettingRunnable.java:29)
        at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
        at java.base/java.lang.Thread.run(Thread.java:829)

Any tip to figure out / debug what I might be doing wrong?

Thanks for the help

After setting the env variable it already worked as expected
KC_SPI_LOGIN_PROVIDER=myFormProvider
similar should also be achievable with build argument:
–spi-login-provider=myFormProvider