XML JUnit Report is no longer supporting comments in <testsuite>. In case you place within <testsuite> </testsuite> a comment, you will get an error (this was working still in 5.1.22):
02:58:52,121 WARN - Processing resource testABC.xml failed.
    java.lang.RuntimeException: javax.xml.stream.XMLStreamException: Unsupported event: <!--BlaBlaBla: 1401927395036-->
        at com.google.common.base.Throwables.propagate(Throwables.java:160)
        at com.pmease.quickbuild.plugin.report.junit.JUnitXMLResourceReader.doRead(JUnitXMLResourceReader.java:71)
        at com.pmease.quickbuild.plugin.report.engine.generator.reader.XMLResourceReader.read(XMLResourceReader.java:39)
        at com.pmease.quickbuild.plugin.report.engine.generator.reader.XMLResourceReader.read(XMLResourceReader.java:21)
        at com.pmease.quickbuild.plugin.report.junit.TestCaseProcessor.processResource(TestCaseProcessor.java:49)
        at com.pmease.quickbuild.plugin.report.engine.generator.AbstractProcessor.doExecute(AbstractProcessor.java:83)
        at com.pmease.quickbuild.plugin.report.engine.generator.GenerateAction.execute(GenerateAction.java:42)
        at com.pmease.quickbuild.plugin.report.engine.generator.AbstractGenerator.doExecute(AbstractGenerator.java:43)
        at com.pmease.quickbuild.plugin.report.engine.generator.GenerateAction.execute(GenerateAction.java:42)
        at com.pmease.quickbuild.plugin.report.engine.generator.DefaultGenerator.generate(DefaultGenerator.java:37)
        at com.pmease.quickbuild.plugin.report.engine.contribution.publisher.AbstractPublisher.doPublish(AbstractPublisher.java:162)
        at com.pmease.quickbuild.plugin.report.junit.JUnitPublisher$$EnhancerByCGLIB$$b2b9c1b2.CGLIB$doPublish$38(<generated>)
        at com.pmease.quickbuild.plugin.report.junit.JUnitPublisher$$EnhancerByCGLIB$$b2b9c1b2$$FastClassByCGLIB$$ed098547.invoke(<generated>)
        at net.sf.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:215)
        at com.pmease.quickbuild.DefaultScriptEngine$Interpolator.intercept(DefaultScriptEngine.java:273)
        at com.pmease.quickbuild.plugin.report.junit.JUnitPublisher$$EnhancerByCGLIB$$b2b9c1b2.doPublish(<generated>)
        at com.pmease.quickbuild.plugin.report.engine.contribution.publisher.AbstractPublisher.run(AbstractPublisher.java:129)
        at com.pmease.quickbuild.plugin.report.junit.JUnitPublisher$$EnhancerByCGLIB$$b2b9c1b2.CGLIB$run$31(<generated>)
        at com.pmease.quickbuild.plugin.report.junit.JUnitPublisher$$EnhancerByCGLIB$$b2b9c1b2$$FastClassByCGLIB$$ed098547.invoke(<generated>)
        at net.sf.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:215)
        at com.pmease.quickbuild.DefaultScriptEngine$Interpolator.intercept(DefaultScriptEngine.java:273)
        at com.pmease.quickbuild.plugin.report.junit.JUnitPublisher$$EnhancerByCGLIB$$b2b9c1b2.run(<generated>)
        at com.pmease.quickbuild.stepsupport.Step.execute(Step.java:539)
        at com.pmease.quickbuild.stepsupport.StepExecutionJob.executeStepAwareJob(StepExecutionJob.java:30)
        at com.pmease.quickbuild.stepsupport.StepAwareJob.executeBuildAwareJob(StepAwareJob.java:45)
        at com.pmease.quickbuild.BuildAwareJob.execute(BuildAwareJob.java:60)
        at com.pmease.quickbuild.grid.GridJob.run(GridJob.java:73)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:439)
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
        at java.util.concurrent.FutureTask.run(FutureTask.java:138)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
        at java.lang.Thread.run(Thread.java:662)
    Caused by: javax.xml.stream.XMLStreamException: Unsupported event: <!--BlaBlaBla: 1401927395036-->
        at org.dom4j.io.STAXEventReader.readNode(STAXEventReader.java:212)
        at org.dom4j.io.STAXEventReader.readElement(STAXEventReader.java:329)
        at com.pmease.quickbuild.plugin.report.junit.JUnitXMLResourceReader$JUnitReader.readElement(JUnitXMLResourceReader.java:37)
        at org.dom4j.io.STAXEventReader.readNode(STAXEventReader.java:198)
        at org.dom4j.io.STAXEventReader.readDocument(STAXEventReader.java:275)
        at org.dom4j.io.STAXEventReader.readDocument(STAXEventReader.java:141)
        at org.dom4j.io.STAXEventReader.readDocument(STAXEventReader.java:102)
        at com.pmease.quickbuild.plugin.report.junit.JUnitXMLResourceReader.doRead(JUnitXMLResourceReader.java:64)
        ... 31 more