groovy.lang.ReadOnlyPropertyException: Cannot set readonly property: a for class: MyClass
	at groovy.lang.MetaClassImpl.setProperty(MetaClassImpl.java:2744)
	at groovy.lang.MetaClassImpl.setProperty(MetaClassImpl.java:3770)
	at MyClass.setProperty(WorkflowScript)
	at org.codehaus.groovy.runtime.InvokerHelper.setProperty(InvokerHelper.java:197)
	at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.setProperty(ScriptBytecodeAdapter.java:484)
	at org.kohsuke.groovy.sandbox.impl.Checker$5.call(Checker.java:300)
	at org.kohsuke.groovy.sandbox.GroovyInterceptor.onSetProperty(GroovyInterceptor.java:68)
	at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.SandboxInterceptor.onSetProperty(SandboxInterceptor.java:182)
	at org.kohsuke.groovy.sandbox.impl.Checker$5.call(Checker.java:297)
	at org.kohsuke.groovy.sandbox.impl.Checker.checkedSetProperty(Checker.java:294)
	at org.kohsuke.groovy.sandbox.impl.Checker$checkedSetProperty$0.callStatic(Unknown Source)
	at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallStatic(CallSiteArray.java:56)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callStatic(AbstractCallSite.java:194)
	at MyClass.<init>(WorkflowScript:4)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at org.codehaus.groovy.reflection.CachedConstructor.invoke(CachedConstructor.java:83)
	at org.codehaus.groovy.runtime.callsite.ConstructorSite$ConstructorSiteNoUnwrapNoCoerce.callConstructor(ConstructorSite.java:105)
	at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallConstructor(CallSiteArray.java:60)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callConstructor(AbstractCallSite.java:235)
	at org.kohsuke.groovy.sandbox.impl.Checker$3.call(Checker.java:194)
	at org.kohsuke.groovy.sandbox.GroovyInterceptor.onNewInstance(GroovyInterceptor.java:40)
	at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.SandboxInterceptor.onNewInstance(SandboxInterceptor.java:128)
	at org.kohsuke.groovy.sandbox.impl.Checker$3.call(Checker.java:191)
	at org.kohsuke.groovy.sandbox.impl.Checker.checkedConstructor(Checker.java:188)
	at com.cloudbees.groovy.cps.sandbox.SandboxInvoker.constructorCall(SandboxInvoker.java:20)
	at WorkflowScript.run(WorkflowScript:8)
	at ___cps.transform___(Native Method)
	at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.dispatchOrArg(FunctionCallBlock.java:96)
	at com.cloudbees.groovy.cps.impl.FunctionCallBlock$ContinuationImpl.fixArg(FunctionCallBlock.java:82)
	at sun.reflect.GeneratedMethodAccessor380.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at com.cloudbees.groovy.cps.impl.ContinuationPtr$ContinuationImpl.receive(ContinuationPtr.java:72)
	at com.cloudbees.groovy.cps.impl.ConstantBlock.eval(ConstantBlock.java:21)
	at com.cloudbees.groovy.cps.Next.step(Next.java:83)
	at com.cloudbees.groovy.cps.Continuable$1.call(Continuable.java:173)
	at com.cloudbees.groovy.cps.Continuable$1.call(Continuable.java:162)
	at org.codehaus.groovy.runtime.GroovyCategorySupport$ThreadCategoryInfo.use(GroovyCategorySupport.java:122)
	at org.codehaus.groovy.runtime.GroovyCategorySupport.use(GroovyCategorySupport.java:261)
	at com.cloudbees.groovy.cps.Continuable.run0(Continuable.java:162)
	at org.jenkinsci.plugins.workflow.cps.SandboxContinuable.access$001(SandboxContinuable.java:19)
	at org.jenkinsci.plugins.workflow.cps.SandboxContinuable$1.call(SandboxContinuable.java:35)
	at org.jenkinsci.plugins.workflow.cps.SandboxContinuable$1.call(SandboxContinuable.java:32)
	at org.jenkinsci.plugins.scriptsecurity.sandbox.groovy.GroovySandbox.runInSandbox(GroovySandbox.java:108)
	at org.jenkinsci.plugins.workflow.cps.SandboxContinuable.run0(SandboxContinuable.java:32)
	at org.jenkinsci.plugins.workflow.cps.CpsThread.runNextChunk(CpsThread.java:174)
	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.run(CpsThreadGroup.java:330)
	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup.access$100(CpsThreadGroup.java:82)
	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:242)
	at org.jenkinsci.plugins.workflow.cps.CpsThreadGroup$2.call(CpsThreadGroup.java:230)
	at org.jenkinsci.plugins.workflow.cps.CpsVmExecutorService$2.call(CpsVmExecutorService.java:64)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at hudson.remoting.SingleLaneExecutorService$1.run(SingleLaneExecutorService.java:112)
	at jenkins.util.ContextResettingExecutorService$1.run(ContextResettingExecutorService.java:28)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)
Finished: FAILURE