WstxValidationException: Unknown reason (at end element </nl:nillableIntElement>) when validating a document with nillable elements

[ppalaga]

This issue occurs when CXF is validating an incoming SOAP message against W3CSchema and the message contains a an xs:dateTime or xs:int elements having xsi:nil="true":

2023-10-28 22:40:16,639 WARN  [org.apa.cxf.pha.PhaseInterceptorChain] (executor-thread-0) Interceptor for {http://nl.schiphol.asb.services/SPLDataService}SPLDataService#{http://nl.schiphol.asb.services/SPLDataService}AddSPLData has thrown exception, unwinding now: org.apache.cxf.interceptor.Fault: Unknown reason (at end element </spl:intElem>)
        at org.apache.cxf.staxutils.validation.Stax2ValidationUtils$2.reportProblem(Stax2ValidationUtils.java:147)
        at com.ctc.wstx.sw.BaseStreamWriter.reportProblem(BaseStreamWriter.java:1230)
        at com.ctc.wstx.msv.GenericMsvValidator.reportError(GenericMsvValidator.java:562)
        at com.ctc.wstx.msv.GenericMsvValidator.reportError(GenericMsvValidator.java:554)
        at com.ctc.wstx.msv.GenericMsvValidator.reportError(GenericMsvValidator.java:548)
        at com.ctc.wstx.msv.GenericMsvValidator.validateElementEnd(GenericMsvValidator.java:390)
        at com.ctc.wstx.sw.BaseNsStreamWriter.doWriteEndTag(BaseNsStreamWriter.java:713)
        at com.ctc.wstx.sw.BaseNsStreamWriter.writeEndElement(BaseNsStreamWriter.java:285)
        at org.apache.cxf.staxutils.StaxUtils.copy(StaxUtils.java:745)
        at org.apache.cxf.staxutils.StaxUtils.copy(StaxUtils.java:707)
        at org.apache.cxf.databinding.source.XMLStreamDataReader.validate(XMLStreamDataReader.java:244)
        at org.apache.cxf.databinding.source.XMLStreamDataReader.read(XMLStreamDataReader.java:115)
        at org.apache.cxf.databinding.source.XMLStreamDataReader.read(XMLStreamDataReader.java:83)
        at org.apache.cxf.databinding.source.XMLStreamDataReader.read(XMLStreamDataReader.java:67)
        at org.apache.cxf.wsdl.interceptors.DocLiteralInInterceptor.handleMessage(DocLiteralInInterceptor.java:192)
        at org.apache.cxf.phase.PhaseInterceptorChain.doIntercept(PhaseInterceptorChain.java:307)
        at org.apache.cxf.transport.ChainInitiationObserver.onMessage(ChainInitiationObserver.java:121)
        at org.apache.cxf.transport.http.AbstractHTTPDestination.invoke(AbstractHTTPDestination.java:265)
        at org.apache.cxf.transport.servlet.ServletController.invokeDestination(ServletController.java:234)
        at org.apache.cxf.transport.servlet.ServletController.invoke(ServletController.java:208)
        at org.apache.cxf.transport.servlet.ServletController.invoke(ServletController.java:160)
        at io.quarkiverse.cxf.transport.CxfHandler.process(CxfHandler.java:288)
        at io.quarkiverse.cxf.transport.CxfHandler.handle(CxfHandler.java:225)
        at io.quarkiverse.cxf.transport.CxfHandler.handle(CxfHandler.java:46)
        at io.vertx.ext.web.impl.BlockingHandlerDecorator.lambda$handle$0(BlockingHandlerDecorator.java:48)
        at io.vertx.core.impl.ContextBase.lambda$executeBlocking$0(ContextBase.java:137)
        at io.vertx.core.impl.ContextInternal.dispatch(ContextInternal.java:264)
        at io.vertx.core.impl.ContextBase.lambda$executeBlocking$1(ContextBase.java:135)
        at io.quarkus.vertx.core.runtime.VertxCoreRecorder$14.runWith(VertxCoreRecorder.java:576)
        at org.jboss.threads.EnhancedQueueExecutor$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:840)

CXF calls validateAgainst(schema) on a writer which gets the events copied from the reader.

A plain Woodstox reproducer is available in PR https://github.com/FasterXML/woodstox/pull/180 . It also makes sure that the failing XML documents are accepted by javax.xml.validation.