RH-SSO の SAML IdP Response で IdentityBrokerException->NullPointerException が発生する

Issue

• 認証に失敗します。

• ログに次の例外があります。

  ERROR [org.keycloak.services.error.KeycloakErrorHandler] (default task-8) Uncaught server error: org.keycloak.broker.provider.IdentityBrokerException: Could not process response from SAML identity provider.
  at org.keycloak.broker.saml.SAMLEndpoint$Binding.handleLoginResponse(SAMLEndpoint.java:469)
  at org.keycloak.broker.saml.SAMLEndpoint$Binding.handleSamlResponse(SAMLEndpoint.java:504)
  at org.keycloak.broker.saml.SAMLEndpoint$Binding.execute(SAMLEndpoint.java:244)
  at org.keycloak.broker.saml.SAMLEndpoint.postBinding(SAMLEndpoint.java:160)
  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
  at java.lang.reflect.Method.invoke(Unknown Source)
  at org.jboss.resteasy.core.MethodInjectorImpl.invoke(MethodInjectorImpl.java:140)
  ...
  Caused by: java.lang.NullPointerException
  at java.util.regex.Matcher.getTextLength(Unknown Source)
  at java.util.regex.Matcher.reset(Unknown Source)
  at java.util.regex.Matcher.<init>(Unknown Source)
  at java.util.regex.Pattern.matcher(Unknown Source)
  at java.util.regex.Pattern.split(Unknown Source)
  at org.keycloak.broker.provider.util.IdentityBrokerState.encoded(IdentityBrokerState.java:41)
  at org.keycloak.services.resources.IdentityBrokerService.parseEncodedSessionCode(IdentityBrokerService.java:987)
  at org.keycloak.services.resources.IdentityBrokerService.authenticated(IdentityBrokerService.java:497)
  at org.keycloak.broker.saml.SAMLEndpoint$Binding.handleLoginResponse(SAMLEndpoint.java:465)
  ... 74 more