java.lang.RuntimeException: java.io.IOException: java.lang.RuntimeException: Failed to serialize hudson.model.Project#builders for class hudson.model.FreeStyleProject
	at hudson.util.PersistedList._onModified(PersistedList.java:183)
	at hudson.util.PersistedList.add(PersistedList.java:72)
	at org.jvnet.hudson.test.JenkinsRule.configRoundtrip(JenkinsRule.java:1086)
	at hudson.plugins.gradle.GradlePluginIntegrationTest.Config roundtrip(GradlePluginIntegrationTest.groovy:180)
Caused by: java.io.IOException: java.lang.RuntimeException: Failed to serialize hudson.model.Project#builders for class hudson.model.FreeStyleProject
	at hudson.XmlFile.write(XmlFile.java:201)
	at hudson.model.AbstractItem.save(AbstractItem.java:483)
	at hudson.model.Job.save(Job.java:196)
	at hudson.model.AbstractProject.save(AbstractProject.java:289)
	at hudson.util.PersistedList.onModified(PersistedList.java:173)
	at hudson.util.PersistedList._onModified(PersistedList.java:181)
	... 3 more
Caused by: java.lang.RuntimeException: Failed to serialize hudson.model.Project#builders for class hudson.model.FreeStyleProject
	at hudson.util.RobustReflectionConverter$2.writeField(RobustReflectionConverter.java:256)
	at hudson.util.RobustReflectionConverter$2.visit(RobustReflectionConverter.java:224)
	at com.thoughtworks.xstream.converters.reflection.PureJavaReflectionProvider.visitSerializableFields(PureJavaReflectionProvider.java:138)
	at hudson.util.RobustReflectionConverter.doMarshal(RobustReflectionConverter.java:209)
	at hudson.util.RobustReflectionConverter.marshal(RobustReflectionConverter.java:150)
	at com.thoughtworks.xstream.core.AbstractReferenceMarshaller.convert(AbstractReferenceMarshaller.java:69)
	at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:58)
	at com.thoughtworks.xstream.core.TreeMarshaller.convertAnother(TreeMarshaller.java:43)
	at com.thoughtworks.xstream.core.TreeMarshaller.start(TreeMarshaller.java:82)
	at com.thoughtworks.xstream.core.AbstractTreeMarshallingStrategy.marshal(AbstractTreeMarshallingStrategy.java:37)
	at com.thoughtworks.xstream.XStream.marshal(XStream.java:1026)
	at com.thoughtworks.xstream.XStream.marshal(XStream.java:1015)
	at com.thoughtworks.xstream.XStream.toXML(XStream.java:988)
	at hudson.XmlFile.write(XmlFile.java:194)
	... 8 more
Caused by: java.lang.UnsupportedOperationException: Refusing to marshal hudson.plugins.gradle.Gradle for security reasons; see https://jenkins.io/redirect/class-filter/
	at hudson.util.XStream2$BlacklistedTypesConverter.marshal(XStream2.java:530)
	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$1.convertAnother(AbstractReferenceMarshaller.java:88)
	at com.thoughtworks.xstream.converters.collections.AbstractCollectionConverter.writeItem(AbstractCollectionConverter.java:64)
	at hudson.util.DescribableList$ConverterImpl.marshal(DescribableList.java:269)
	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)
	... 21 more