okhttp 3.12.12 stacktrace when running with java 7

stacktrace

Exception in thread "main" java.lang.NoClassDefFoundError: java/time/Duration
	at java.lang.Class.getDeclaredMethods0(Native Method)
	at java.lang.Class.privateGetDeclaredMethods(Class.java:2625)
	at java.lang.Class.privateGetPublicMethods(Class.java:2743)
	at java.lang.Class.getMethods(Class.java:1480)
	at java.beans.Introspector.getPublicDeclaredMethods(Introspector.java:1280)
	at java.beans.Introspector.getTargetMethodInfo(Introspector.java:1141)
	at java.beans.Introspector.getBeanInfo(Introspector.java:416)
	at java.beans.Introspector.getBeanInfo(Introspector.java:163)
	at groovy.lang.MetaClassImpl$15.run(MetaClassImpl.java:3328)
	at java.security.AccessController.doPrivileged(Native Method)
	at groovy.lang.MetaClassImpl.addProperties(MetaClassImpl.java:3326)
	at groovy.lang.MetaClassImpl.initialize(MetaClassImpl.java:3303)
	at org.codehaus.groovy.reflection.ClassInfo.getMetaClassUnderLock(ClassInfo.java:289)
	at org.codehaus.groovy.reflection.ClassInfo.getMetaClass(ClassInfo.java:331)
	at org.codehaus.groovy.runtime.metaclass.MetaClassRegistryImpl.getMetaClass(MetaClassRegistryImpl.java:277)
	at org.codehaus.groovy.runtime.InvokerHelper.getMetaClass(InvokerHelper.java:905)
	at org.codehaus.groovy.runtime.callsite.CallSiteArray.createCallConstructorSite(CallSiteArray.java:86)
	at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallConstructor(CallSiteArray.java:59)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callConstructor(AbstractCallSite.java:238)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callConstructor(AbstractCallSite.java:242)
	at iteego.slack.SlackClientCommand.call(SlackClientCommand.groovy:53)
	at iteego.slack.SlackClientCommand.call(SlackClientCommand.groovy)
	at picocli.CommandLine.executeUserObject(CommandLine.java:1933)
	at picocli.CommandLine.access$1100(CommandLine.java:145)
	at picocli.CommandLine$RunLast.executeUserObjectOfLastSubcommandWithSameParent(CommandLine.java:2332)
	at picocli.CommandLine$RunLast.handle(CommandLine.java:2326)
	at picocli.CommandLine$RunLast.handle(CommandLine.java:2291)
	at picocli.CommandLine$AbstractParseResultHandler.execute(CommandLine.java:2159)
	at picocli.CommandLine.execute(CommandLine.java:2058)
	at picocli.CommandLine$execute.call(Unknown Source)
	at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:47)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:116)
	at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:128)
	at iteego.slack.SlackClientCommand.main(SlackClientCommand.groovy:44)
Caused by: java.lang.ClassNotFoundException: java.time.Duration
	at java.net.URLClassLoader$1.run(URLClassLoader.java:367)
	at java.net.URLClassLoader$1.run(URLClassLoader.java:356)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:355)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:323)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
	... 34 more