When I try to save the configuration for a task which uses the tap plugin I get the following stack:

Status Code: 500
Exception:
Stacktrace:

java.lang.RuntimeException: Failed to serialize hudson.model.Project#publishers for class hudson.model.FreeStyleProject
at hudson.util.RobustReflectionConverter$2.writeField(RobustReflectionConverter.java:167)
at hudson.util.RobustReflectionConverter$2.visit(RobustReflectionConverter.java:135)
at com.thoughtworks.xstream.converters.reflection.PureJavaReflectionProvider.visitSerializableFields(PureJavaReflectionProvider.java:130)
at hudson.util.RobustReflectionConverter.doMarshal(RobustReflectionConverter.java:120)
at hudson.util.RobustReflectionConverter.marshal(RobustReflectionConverter.java:94)
at com.thoughtworks.xstream.core.AbstractReferenceMarshaller.convert(AbstractReferenceMarshaller.java:68)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:78)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:63)
at com.thoughtworks.xstream.core.TreeMarshaller.start(TreeMarshaller.java:98)
at com.thoughtworks.xstream.core.AbstractTreeMarshallingStrategy.marshal(AbstractTreeMarshallingStrategy.java:38)
at com.thoughtworks.xstream.XStream.marshal(XStream.java:840)
at com.thoughtworks.xstream.XStream.marshal(XStream.java:829)
at com.thoughtworks.xstream.XStream.toXML(XStream.java:804)
at hudson.XmlFile.write(XmlFile.java:173)
at hudson.model.AbstractItem.save(AbstractItem.java:419)
at hudson.model.Job.save(Job.java:150)
at hudson.model.AbstractProject.setScm(AbstractProject.java:1379)
at hudson.model.AbstractProject.submit(AbstractProject.java:1688)
at hudson.model.Project.submit(Project.java:192)
at hudson.model.Job.doConfigSubmit(Job.java:965)
at hudson.model.AbstractProject.doConfigSubmit(AbstractProject.java:643)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.kohsuke.stapler.Function$InstanceFunction.invoke(Function.java:282)
at org.kohsuke.stapler.Function.bindAndInvoke(Function.java:149)
at org.kohsuke.stapler.Function.bindAndInvokeAndServeResponse(Function.java:88)
at org.kohsuke.stapler.MetaClass$1.doDispatch(MetaClass.java:104)
at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:53)
at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:561)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:646)
at org.kohsuke.stapler.MetaClass$6.doDispatch(MetaClass.java:234)
at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:53)
at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:561)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:646)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:477)
at org.kohsuke.stapler.Stapler.service(Stapler.java:159)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:45)
at winstone.ServletConfiguration.execute(ServletConfiguration.java:249)
at winstone.RequestDispatcher.forward(RequestDispatcher.java:335)
at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:378)
at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:94)
at hudson.util.PluginServletFilter.doFilter(PluginServletFilter.java:86)
at winstone.FilterConfiguration.execute(FilterConfiguration.java:195)
at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:368)
at hudson.security.csrf.CrumbFilter.doFilter(CrumbFilter.java:47)
at winstone.FilterConfiguration.execute(FilterConfiguration.java:195)
at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:368)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:84)
at hudson.security.ChainedServletFilter.doFilter(ChainedServletFilter.java:76)
at hudson.security.HudsonFilter.doFilter(HudsonFilter.java:164)
at winstone.FilterConfiguration.execute(FilterConfiguration.java:195)
at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:368)
at hudson.util.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:81)
at winstone.FilterConfiguration.execute(FilterConfiguration.java:195)
at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:368)
at winstone.RequestDispatcher.forward(RequestDispatcher.java:333)
at winstone.RequestHandlerThread.processRequest(RequestHandlerThread.java:244)
at winstone.RequestHandlerThread.run(RequestHandlerThread.java:150)
at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.RuntimeException: Failed to serialize org.tap4j.plugin.TapPublisher#remoteCallable for class org.tap4j.plugin.TapPublisher
at hudson.util.RobustReflectionConverter$2.writeField(RobustReflectionConverter.java:167)
at hudson.util.RobustReflectionConverter$2.visit(RobustReflectionConverter.java:135)
at com.thoughtworks.xstream.converters.reflection.PureJavaReflectionProvider.visitSerializableFields(PureJavaReflectionProvider.java:130)
at hudson.util.RobustReflectionConverter.doMarshal(RobustReflectionConverter.java:120)
at hudson.util.RobustReflectionConverter.marshal(RobustReflectionConverter.java:94)
at com.thoughtworks.xstream.core.AbstractReferenceMarshaller.convert(AbstractReferenceMarshaller.java:68)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:78)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:63)
at com.thoughtworks.xstream.converters.collections.AbstractCollectionConverter.writeItem(AbstractCollectionConverter.java:64)
at hudson.util.DescribableList$ConverterImpl.marshal(DescribableList.java:241)
at com.thoughtworks.xstream.core.AbstractReferenceMarshaller.convert(AbstractReferenceMarshaller.java:68)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:78)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:63)
at hudson.util.RobustReflectionConverter.marshallField(RobustReflectionConverter.java:175)
at hudson.util.RobustReflectionConverter$2.writeField(RobustReflectionConverter.java:163)
... 60 more
Caused by: java.lang.RuntimeException: Failed to serialize org.tap4j.plugin.TapRemoteCallable#listener for class org.tap4j.plugin.TapRemoteCallable
at hudson.util.RobustReflectionConverter$2.writeField(RobustReflectionConverter.java:167)
at hudson.util.RobustReflectionConverter$2.visit(RobustReflectionConverter.java:135)
at com.thoughtworks.xstream.converters.reflection.PureJavaReflectionProvider.visitSerializableFields(PureJavaReflectionProvider.java:130)
at hudson.util.RobustReflectionConverter.doMarshal(RobustReflectionConverter.java:120)
at hudson.util.RobustReflectionConverter.marshal(RobustReflectionConverter.java:94)
at com.thoughtworks.xstream.core.AbstractReferenceMarshaller.convert(AbstractReferenceMarshaller.java:68)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:78)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:63)
at hudson.util.RobustReflectionConverter.marshallField(RobustReflectionConverter.java:175)
at hudson.util.RobustReflectionConverter$2.writeField(RobustReflectionConverter.java:163)
... 74 more
Caused by: com.thoughtworks.xstream.converters.ConversionException: Could not call hudson.model.StreamBuildListener.writeObject() : Could not call hudson.remoting.RemoteOutputStream.writeObject() : null
---- Debugging information ----
message : Could not call hudson.remoting.RemoteOutputStream.writeObject()
cause-exception : java.lang.NullPointerException
cause-message : null
-------------------------------
message : Could not call hudson.model.StreamBuildListener.writeObject()
cause-exception : com.thoughtworks.xstream.converters.ConversionException
cause-message : Could not call hudson.remoting.RemoteOutputStream.writeObject() : null
-------------------------------
at com.thoughtworks.xstream.converters.reflection.SerializationMethodInvoker.callWriteObject(SerializationMethodInvoker.java:104)
at com.thoughtworks.xstream.converters.reflection.SerializableConverter.doMarshal(SerializableConverter.java:215)
at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.marshal(AbstractReflectionConverter.java:58)
at com.thoughtworks.xstream.core.AbstractReferenceMarshaller.convert(AbstractReferenceMarshaller.java:68)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:78)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:63)
at hudson.util.RobustReflectionConverter.marshallField(RobustReflectionConverter.java:175)
at hudson.util.RobustReflectionConverter$2.writeField(RobustReflectionConverter.java:163)
... 83 more
Caused by: com.thoughtworks.xstream.converters.ConversionException: Could not call hudson.remoting.RemoteOutputStream.writeObject() : null
---- Debugging information ----
message : Could not call hudson.remoting.RemoteOutputStream.writeObject()
cause-exception : java.lang.NullPointerException
cause-message : null
-------------------------------
at com.thoughtworks.xstream.converters.reflection.SerializationMethodInvoker.callWriteObject(SerializationMethodInvoker.java:104)
at com.thoughtworks.xstream.converters.reflection.SerializableConverter.doMarshal(SerializableConverter.java:215)
at com.thoughtworks.xstream.converters.reflection.AbstractReflectionConverter.marshal(AbstractReflectionConverter.java:58)
at com.thoughtworks.xstream.core.AbstractReferenceMarshaller.convert(AbstractReferenceMarshaller.java:68)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:78)
at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:63)
at com.thoughtworks.xstream.converters.reflection.SerializableConverter$1.writeToStream(SerializableConverter.java:104)
at com.thoughtworks.xstream.core.util.CustomObjectOutputStream.writeObjectOverride(CustomObjectOutputStream.java:84)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:322)
at hudson.util.StreamTaskListener.writeObject(StreamTaskListener.java:161)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.thoughtworks.xstream.converters.reflection.SerializationMethodInvoker.callWriteObject(SerializationMethodInvoker.java:100)
... 90 more
Caused by: java.lang.NullPointerException
at hudson.remoting.RemoteOutputStream.writeObject(RemoteOutputStream.java:82)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.thoughtworks.xstream.converters.reflection.SerializationMethodInvoker.callWriteObject(SerializationMethodInvoker.java:100)
... 104 more