added deprecation warning

Author: daspilker

job-dsl-core/src/main/groovy/javaposse/jobdsl/dsl/jobs/MultiJob.groovy

@@ -1,5 +1,6 @@
 package javaposse.jobdsl.dsl.jobs
 
+import hudson.util.VersionNumber
 import javaposse.jobdsl.dsl.ContextHelper
 import javaposse.jobdsl.dsl.DslContext
 import javaposse.jobdsl.dsl.Job
@@ -10,6 +11,10 @@ import javaposse.jobdsl.dsl.helpers.step.MultiJobStepContext
 class MultiJob extends Job {
     MultiJob(JobManagement jobManagement) {
         super(jobManagement)
+
+        if (jobManagement.getPluginVersion('jenkins-multijob-plugin')?.isOlderThan(new VersionNumber('1.16'))) {
+            jobManagement.logDeprecationWarning('support for MultiJob plugin versions 1.15 and earlier')
+        }
     }
 
     void steps(@DslContext(MultiJobStepContext) Closure closure) {