deprecated support for older versions of SSH Agent plugin

Author: daspilker

docs/Home.md

@@ -34,6 +34,9 @@ Browse the Jenkins issue tracker to see any [open issues](https://issues.jenkins
    ([#978](https://github.com/jenkinsci/job-dsl-plugin/pull/978))
  * Enhanced support for the [SSH Agent Plugin](https://wiki.jenkins-ci.org/display/JENKINS/SSH+Agent+Plugin)
    ([#980](https://github.com/jenkinsci/job-dsl-plugin/pull/980))
+ * Support for the older versions of the
+   [SSH Agent Plugin](https://wiki.jenkins-ci.org/display/JENKINS/SSH+Agent+Plugin),
+   see [Migration](Migration#migrating-to-156)
 * 1.55 (January 03 2016)
  * Updated optional
    [Config File Provider Plugin](https://wiki.jenkins-ci.org/display/JENKINS/Config+File+Provider+Plugin) dependency to

docs/Migration.md

@@ -1,3 +1,11 @@
+## Migrating to 1.56
+
+### SSH Agent
+
+Support for versions older than 1.5 of the
+[SSH Agent Plugin](https://wiki.jenkins-ci.org/display/JENKINS/SSH+Agent+Plugin) is [[deprecated|Deprecation-Policy]]
+and will be removed.
+
 ## Migrating to 1.55
 
 ### ScriptRequest

job-dsl-core/src/main/groovy/javaposse/jobdsl/dsl/helpers/wrapper/WrapperContext.groovy

@@ -186,6 +186,7 @@ class WrapperContext extends AbstractExtensibleContext {
      */
     @RequiresPlugin(id = 'ssh-agent')
     void sshAgent(String credentials) {
+        jobManagement.logPluginDeprecationWarning('ssh-agent', '1.5')
         Preconditions.checkNotNull(credentials, 'credentials must not be null')
 
         wrapperNodes << new NodeBuilder().'com.cloudbees.jenkins.plugins.sshagent.SSHAgentBuildWrapper' {

job-dsl-core/src/test/groovy/javaposse/jobdsl/dsl/helpers/wrapper/WrapperContextSpec.groovy

@@ -399,6 +399,7 @@ class WrapperContextSpec extends Specification {
         context.wrapperNodes[0].name() == 'com.cloudbees.jenkins.plugins.sshagent.SSHAgentBuildWrapper'
         context.wrapperNodes[0].user[0].value() == 'acme'
         1 * mockJobManagement.requirePlugin('ssh-agent')
+        1 * mockJobManagement.logPluginDeprecationWarning('ssh-agent', '1.5')
     }
 
     def 'sshAgent with multiple credentials'() {