IdP/SP metadata import feature is broken in RH-SSO 7.6.3

Issue

• IdP/SP metadata import feature is broken in RH-SSO 7.6.3

RH-SSO 7.6.3 emits NPE when an Admin try to import SAML IdP/SP metadata.

2023-06-05 18:12:30,676 ERROR [org.keycloak.services.error.KeycloakErrorHandler] (default task-6) Uncaught server error: java.lang.NullPointerException
        at org.jboss.resteasy.plugins.providers.multipart.Mime4JWorkaround$CustomTempFileStorageProvider.createStorageOutputStream(Mime4JWorkaround.java:134)
        at org.apache.james.mime4j.storage.ThresholdStorageProvider$ThresholdStorageOutputStream.write0(ThresholdStorageProvider.java:113)
        at org.apache.james.mime4j.storage.StorageOutputStream.write(StorageOutputStream.java:119)
        at org.apache.james.mime4j.util.ContentUtil.copy(ContentUtil.java:84)
        at org.apache.james.mime4j.storage.AbstractStorageProvider.store(AbstractStorageProvider.java:57)
        at org.apache.james.mime4j.storage.StorageBodyFactory.binaryBody(StorageBodyFactory.java:94)
        at org.jboss.resteasy.plugins.providers.multipart.Mime4jWorkaroundBinaryEntityBuilder.body(Mime4jWorkaroundBinaryEntityBuilder.java:177)
        at org.apache.james.mime4j.parser.MimeStreamParser.parse(MimeStreamParser.java:133)
        at org.jboss.resteasy.plugins.providers.multipart.Mime4JWorkaround.parseMessage(Mime4JWorkaround.java:95)
        at org.jboss.resteasy.plugins.providers.multipart.MultipartInputImpl.parse(MultipartInputImpl.java:102)
        at org.jboss.resteasy.plugins.providers.multipart.MultipartFormDataReader.readFrom(MultipartFormDataReader.java:53)
        at org.jboss.resteasy.plugins.providers.multipart.MultipartFormDataReader.readFrom(MultipartFormDataReader.java:23)
        at org.jboss.resteasy.core.interception.AbstractReaderInterceptorContext.readFrom(AbstractReaderInterceptorContext.java:66)
        at org.jboss.resteasy.core.interception.ServerReaderInterceptorContext.readFrom(ServerReaderInterceptorContext.java:61)
        at org.jboss.resteasy.core.interception.AbstractReaderInterceptorContext.proceed(AbstractReaderInterceptorContext.java:56)
        at org.jboss.resteasy.security.doseta.DigitalVerificationInterceptor.aroundReadFrom(DigitalVerificationInterceptor.java:36)
        at org.jboss.resteasy.core.interception.AbstractReaderInterceptorContext.proceed(AbstractReaderInterceptorContext.java:59)
        at org.jboss.resteasy.core.MessageBodyParameterInjector.inject(MessageBodyParameterInjector.java:198)
        at org.jboss.resteasy.core.MethodInjectorImpl.injectArguments(MethodInjectorImpl.java:91)
        at org.jboss.resteasy.core.MethodInjectorImpl.invoke(MethodInjectorImpl.java:113)
        at org.jboss.resteasy.core.ResourceMethodInvoker.internalInvokeOnTarget(ResourceMethodInvoker.java:546)
        at org.jboss.resteasy.core.ResourceMethodInvoker.invokeOnTargetAfterFilter(ResourceMethodInvoker.java:435)
        at org.jboss.resteasy.core.ResourceMethodInvoker.lambda$invokeOnTarget$0(ResourceMethodInvoker.java:396)
        at org.jboss.resteasy.core.interception.PreMatchContainerRequestContext.filter(PreMatchContainerRequestContext.java:358)
        at org.jboss.resteasy.core.ResourceMethodInvoker.invokeOnTarget(ResourceMethodInvoker.java:398)
        at org.jboss.resteasy.core.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:365)
        at org.jboss.resteasy.core.ResourceLocatorInvoker.invokeOnTargetObject(ResourceLocatorInvoker.java:150)
        at org.jboss.resteasy.core.ResourceLocatorInvoker.invoke(ResourceLocatorInvoker.java:110)
        at org.jboss.resteasy.core.ResourceLocatorInvoker.invokeOnTargetObject(ResourceLocatorInvoker.java:141)
        at org.jboss.resteasy.core.ResourceLocatorInvoker.invoke(ResourceLocatorInvoker.java:110)
        at org.jboss.resteasy.core.ResourceLocatorInvoker.invokeOnTargetObject(ResourceLocatorInvoker.java:141)
        at org.jboss.resteasy.core.ResourceLocatorInvoker.invoke(ResourceLocatorInvoker.java:104)
        at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:440)
        at org.jboss.resteasy.core.SynchronousDispatcher.lambda$invoke$4(SynchronousDispatcher.java:229)
        at org.jboss.resteasy.core.SynchronousDispatcher.lambda$preprocess$0(SynchronousDispatcher.java:135)
        at org.jboss.resteasy.core.interception.PreMatchContainerRequestContext.filter(PreMatchContainerRequestContext.java:358)
        at org.jboss.resteasy.core.SynchronousDispatcher.preprocess(SynchronousDispatcher.java:138)
        at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:215)
        at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.service(ServletContainerDispatcher.java:245)
        at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:61)
        at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:56)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:590)
(omitted)