java.lang.NullPointerException
 at org.jenkinsci.lib.envinject.EnvInjectAction.writeReplace(EnvInjectAction.java:144)
 at sun.reflect.GeneratedMethodAccessor369.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
 at java.lang.reflect.Method.invoke(Method.java:498)
 at com.thoughtworks.xstream.converters.reflection.SerializationMethodInvoker.callWriteReplace(SerializationMethodInvoker.java:89)
 at hudson.util.RobustReflectionConverter.marshal(RobustReflectionConverter.java:141)
 at com.thoughtworks.xstream.core.AbstractReferenceMarshaller.convert(AbstractReferenceMarshaller.java:69)
 at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:58)
 at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:43)
 at com.thoughtworks.xstream.core.AbstractReferenceMarshaller$1.convertAnother(AbstractReferenceMarshaller.java:88)
 at com.thoughtworks.xstream.converters.collections.AbstractCollectionConverter.writeItem(AbstractCollectionConverter.java:64)
 at com.thoughtworks.xstream.converters.collections.CollectionConverter.marshal(CollectionConverter.java:74)
 at com.thoughtworks.xstream.core.AbstractReferenceMarshaller.convert(AbstractReferenceMarshaller.java:69)
 at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:58)
 at com.thoughtworks.xstream.core.AbstractReferenceMarshaller$1.convertAnother(AbstractReferenceMarshaller.java:84)
 at hudson.util.RobustReflectionConverter.marshallField(RobustReflectionConverter.java:265)
 at hudson.util.RobustReflectionConverter$2.writeField(RobustReflectionConverter.java:252)
 at hudson.util.RobustReflectionConverter$2.visit(RobustReflectionConverter.java:224)
 at com.thoughtworks.xstream.converters.reflection.PureJavaReflectionProvider.visitSerializableFields(PureJavaReflectionProvider.java:138)
 at hudson.util.RobustReflectionConverter.doMarshal(RobustReflectionConverter.java:209)
 at hudson.util.RobustReflectionConverter.marshal(RobustReflectionConverter.java:150)
 at com.thoughtworks.xstream.core.AbstractReferenceMarshaller.convert(AbstractReferenceMarshaller.java:69)
 at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:58)
 at com.thoughtworks.xstream.core.AbstractReferenceMarshaller$1.convertAnother(AbstractReferenceMarshaller.java:84)
 at hudson.util.RobustReflectionConverter.marshallField(RobustReflectionConverter.java:265)
 at hudson.util.RobustReflectionConverter$2.writeField(RobustReflectionConverter.java:252)
 at hudson.util.RobustReflectionConverter$2.visit(RobustReflectionConverter.java:224)
 at com.thoughtworks.xstream.converters.reflection.PureJavaReflectionProvider.visitSerializableFields(PureJavaReflectionProvider.java:138)
 at hudson.util.RobustReflectionConverter.doMarshal(RobustReflectionConverter.java:209)
 at hudson.util.RobustReflectionConverter.marshal(RobustReflectionConverter.java:150)
 at com.thoughtworks.xstream.core.AbstractReferenceMarshaller.convert(AbstractReferenceMarshaller.java:69)
 at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:58)
 at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:43)
 at com.thoughtworks.xstream.core.AbstractReferenceMarshaller$1.convertAnother(AbstractReferenceMarshaller.java:88)
 at com.thoughtworks.xstream.converters.collections.AbstractCollectionConverter.writeItem(AbstractCollectionConverter.java:64)
 at com.thoughtworks.xstream.converters.collections.CollectionConverter.marshal(CollectionConverter.java:74)
 at com.thoughtworks.xstream.core.AbstractReferenceMarshaller.convert(AbstractReferenceMarshaller.java:69)
 at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:58)
 at com.thoughtworks.xstream.core.AbstractReferenceMarshaller$1.convertAnother(AbstractReferenceMarshaller.java:84)
 at hudson.util.RobustReflectionConverter.marshallField(RobustReflectionConverter.java:265)
 at hudson.util.RobustReflectionConverter$2.writeField(RobustReflectionConverter.java:252)
 at hudson.util.RobustReflectionConverter$2.visit(RobustReflectionConverter.java:224)
 at com.thoughtworks.xstream.converters.reflection.PureJavaReflectionProvider.visitSerializableFields(PureJavaReflectionProvider.java:138)
 at hudson.util.RobustReflectionConverter.doMarshal(RobustReflectionConverter.java:209)
 at hudson.util.RobustReflectionConverter.marshal(RobustReflectionConverter.java:150)
 at com.thoughtworks.xstream.core.AbstractReferenceMarshaller.convert(AbstractReferenceMarshaller.java:69)
 at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:58)
 at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:43)
 at com.thoughtworks.xstream.core.TreeMarshaller.start(TreeMarshaller.java:82)
 at com.thoughtworks.xstream.core.AbstractTreeMarshallingStrategy.marshal(AbstractTreeMarshallingStrategy.java:37)
 at com.thoughtworks.xstream.XStream.marshal(XStream.java:1026)
 at com.thoughtworks.xstream.XStream.marshal(XStream.java:1015)
 at com.thoughtworks.xstream.XStream.toXML(XStream.java:988)
 at hudson.XmlFile.write(XmlFile.java:171)
 at hudson.model.Run.save(Run.java:1933)
 at hudson.model.Saveable$save.call(Unknown Source)
 at Script1.run(Script1.groovy:31)
 at groovy.lang.GroovyShell.evaluate(GroovyShell.java:585)
 at groovy.lang.GroovyShell.evaluate(GroovyShell.java:623)
 at groovy.lang.GroovyShell.evaluate(GroovyShell.java:594)
 at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.SecureGroovyScript.evaluate(SecureGroovyScript.java:170)
 at hudson.plugins.groovy.SystemGroovy.run(SystemGroovy.java:95)
 at hudson.plugins.groovy.SystemGroovy.perform(SystemGroovy.java:59)
 at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:20)
 at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:736)
 at hudson.model.Build$BuildExecution.build(Build.java:206)
 at hudson.model.Build$BuildExecution.doRun(Build.java:163)
 at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:496)
 at hudson.model.Run.execute(Run.java:1737)
 at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
 at hudson.model.ResourceController.execute(ResourceController.java:97)
 at hudson.model.Executor.run(Executor.java:421)