Added gerrit get change function

Change-Id: Ie19216a5d8f13267dcbe5d2fdb4d317ee0cac95f
diff --git a/src/com/mirantis/mk/Gerrit.groovy b/src/com/mirantis/mk/Gerrit.groovy
index c731df3..bd2c4d5 100644
--- a/src/com/mirantis/mk/Gerrit.groovy
+++ b/src/com/mirantis/mk/Gerrit.groovy
@@ -132,6 +132,22 @@
     return false
 }
 
+/**
+ * Return gerrit change object from gerrit API
+ * @param gerritHost gerrit host (usually GERRIT_HOST property)
+ * @param gerritName gerrit user name (usually GERRIT_NAME property)
+ * @param gerritChangeNumber gerrit change number (usually GERRIT_CHANGE_NUMBER property)
+ * @param credentialsId jenkins credentials id for gerrit
+ * @return gerrit change object
+ */
+def getGerritChange(gerritHost, gerritName, gerritChangeNumber, credentialsId){
+    def common = new com.mirantis.mk.Common()
+    def ssh = new com.mirantis.mk.Ssh()
+    ssh.prepareSshAgentKey(credentialsId)
+    ssh.ensureKnownHosts(gerritHost)
+    return common.parseJSON(ssh.agentSh(String.format("ssh -p 29418 %s@%s gerrit query --format=JSON change:%s", gerritName, gerritHost, gerritChangeNumber)))
+}
+
 @NonCPS
 def _getGerritParamsFromUrl(gitUrl){
     def gitUrlPattern = Pattern.compile("(.+):\\/\\/(.+)@(.+):(.+)\\/(.+)")