I have configured SSSD provider and try to login with user without mail attribute filled NullPointerException occured.
The more important issue is, that the user is imported to RH-SSO and when try to list users, same exception occurs and no user is showed. I can only delete the SSSD provider to be able to show users.

KC-SERVICES0013: Failed authentication: java.lang.NullPointerException
at org.keycloak.federation.sssd.SSSDFederationProvider.isValid(SSSDFederationProvider.java:162)
at org.keycloak.federation.sssd.SSSDFederationProvider.validateAndProxy(SSSDFederationProvider.java:185)
at org.keycloak.federation.sssd.SSSDFederationProvider.importUserToKeycloak(SSSDFederationProvider.java:130)
at org.keycloak.federation.sssd.SSSDFederationProvider.findOrCreateAuthenticatedUser(SSSDFederationProvider.java:110)
at org.keycloak.federation.sssd.SSSDFederationProvider.getUserByUsername(SSSDFederationProvider.java:73)
at org.keycloak.storage.UserStorageManager.getUserByUsername(UserStorageManager.java:312)
at org.keycloak.models.cache.infinispan.UserCacheSession.getUserByUsername(UserCacheSession.java:246)
at org.keycloak.models.utils.KeycloakModelUtils.findUserByNameOrEmail(KeycloakModelUtils.java:205)
at org.keycloak.authentication.authenticators.browser.AbstractUsernameFormAuthenticator.validateUserAndPassword(AbstractUsernameFormAuthenticator.java:133)
at org.keycloak.authentication.authenticators.browser.UsernamePasswordForm.validateForm(UsernamePasswordForm.java:56)
at org.keycloak.authentication.authenticators.browser.UsernamePasswordForm.action(UsernamePasswordForm.java:49)
at org.keycloak.authentication.DefaultAuthenticationFlow.processAction(DefaultAuthenticationFlow.java:92)
at org.keycloak.authentication.DefaultAuthenticationFlow.processAction(DefaultAuthenticationFlow.java:76)
at org.keycloak.authentication.AuthenticationProcessor.authenticationAction(AuthenticationProcessor.java:759)
at org.keycloak.services.resources.LoginActionsService.processFlow(LoginActionsService.java:365)
at org.keycloak.services.resources.LoginActionsService.processAuthentication(LoginActionsService.java:347)
at org.keycloak.services.resources.LoginActionsService.authenticateForm(LoginActionsService.java:401)
at sun.reflect.GeneratedMethodAccessor573.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:55)
at java.lang.reflect.Method.invoke(Method.java:508)
at org.jboss.resteasy.core.MethodInjectorImpl.invoke(MethodInjectorImpl.java:139)
at org.jboss.resteasy.core.ResourceMethodInvoker.invokeOnTarget(ResourceMethodInvoker.java:295)
at org.jboss.resteasy.core.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:249)
at org.jboss.resteasy.core.ResourceLocatorInvoker.invokeOnTargetObject(ResourceLocatorInvoker.java:138)
at org.jboss.resteasy.core.ResourceLocatorInvoker.invoke(ResourceLocatorInvoker.java:101)
at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:402)
at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:209)
at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.service(ServletContainerDispatcher.java:221)
at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:56)
at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:51)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:129)
at org.keycloak.services.filters.KeycloakSessionServletFilter.doFilter(KeycloakSessionServletFilter.java:90)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
at io.undertow.servlet.handlers.FilterHandler.handleRequest(FilterHandler.java:84)
at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62)
at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
at org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:131)
at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:57)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:46)
at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:64)
at io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:60)
at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:77)
at io.undertow.security.handlers.NotificationReceiverHandler.handleRequest(NotificationReceiverHandler.java:50)
at io.undertow.security.handlers.AbstractSecurityContextAssociationHandler.handleRequest(AbstractSecurityContextAssociationHandler.java:43)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:61)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:285)
at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:264)
at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:81)
at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:175)
at io.undertow.server.Connectors.executeRootHandler(Connectors.java:207)
at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:802)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1153)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.lang.Thread.run(Thread.java:785)