Using the new workflow plugin, the ZenTimestamper fails with a class cast exception, since it seems to assume that this cast never fails
https://github.com/jenkinsci/zentimestamp-plugin/blob/master/src/main/java/hudson/plugins/zentimestamp/ZenTimestampEnvironmentContributor.java#L23

Running: Allocate node : Start
Running on master in C:\Jenkins\workspace\Demo workflow
Running: Allocate node : Body : Start
Running: Subversion
Running: Allocate node : Body : End
Running: Allocate node : End
Running: End of Workflow
java.lang.ClassCastException: org.jenkinsci.plugins.workflow.job.WorkflowRun cannot be cast to hudson.model.AbstractBuild
at hudson.plugins.zentimestamp.ZenTimestampEnvironmentContributor.buildEnvironmentFor(ZenTimestampEnvironmentContributor.java:23)
at hudson.model.Run.getEnvironment(Run.java:2224)
at hudson.scm.SubversionSCM.checkout(SubversionSCM.java:827)
at org.jenkinsci.plugins.workflow.steps.scm.SCMStep.checkout(SCMStep.java:106)
at org.jenkinsci.plugins.workflow.steps.scm.SCMStep$StepExecutionImpl.run(SCMStep.java:80)
at org.jenkinsci.plugins.workflow.steps.scm.SCMStep$StepExecutionImpl.run(SCMStep.java:70)
at org.jenkinsci.plugins.workflow.steps.AbstractSynchronousStepExecution.start(AbstractSynchronousStepExecution.java:34)
at org.jenkinsci.plugins.workflow.cps.DSL.invokeMethod(DSL.java:136)
at org.jenkinsci.plugins.workflow.cps.CpsScript.invokeMethod(CpsScript.java:98)
at org.codehaus.groovy.runtime.callsite.PogoMetaClassSite.call(PogoMetaClassSite.java:45)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:42)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:108)
at com.cloudbees.groovy.cps.sandbox.DefaultInvoker.methodCall(DefaultInvoker.java:15)
at WorkflowScript.run(WorkflowScript:2)