Allowing for custom flags in software upgrade job

Change-Id: Ic6fd92062dac2c6d93f48e7cc498f8054afde249
diff --git a/jjb/pipeline/voltha/voltha-2.8/software-upgrades.groovy b/jjb/pipeline/voltha/voltha-2.8/software-upgrades.groovy
index 8cae8d6..9b59ae5 100644
--- a/jjb/pipeline/voltha/voltha-2.8/software-upgrades.groovy
+++ b/jjb/pipeline/voltha/voltha-2.8/software-upgrades.groovy
@@ -33,16 +33,16 @@
       _TAG=kail-${name} kail -n ${infraNamespace} -n ${volthaNamespace} > ${logsDir}/onos-voltha-startup-combined.log &
       """
       def extraHelmFlags = extraHelmFlags.trim()
-      extraHelmFlags = extraHelmFlags + " --set global.log_level=${logLevel.toUpperCase()},onu=1,pon=1 --set onos-classic.replicas=3,onos-classic.atomix.replicas=3 "
+      extraHelmFlags = " --set global.log_level=${logLevel.toUpperCase()},onu=1,pon=1 --set onos-classic.replicas=3,onos-classic.atomix.replicas=3 " + extraHelmFlags
 
-      extraHelmFlags = extraHelmFlags + " --set onos-classic.onosSshPort=30115 --set onos-classic.onosApiPort=30120 "
-      extraHelmFlags = extraHelmFlags + " --set voltha.onos_classic.replicas=3"
+      extraHelmFlags = " --set onos-classic.onosSshPort=30115 --set onos-classic.onosApiPort=30120 " + extraHelmFlags
+      extraHelmFlags = " --set voltha.onos_classic.replicas=3 " + extraHelmFlags
       //ONOS custom image handling
       if ( onosImg.trim() != '' ) {
          String[] split;
          onosImg = onosImg.trim()
          split = onosImg.split(':')
-        extraHelmFlags = extraHelmFlags + "--set onos-classic.image.repository=" + split[0] +",onos-classic.image.tag=" + split[1] + " "
+        extraHelmFlags = extraHelmFlags + " --set onos-classic.image.repository=" + split[0] +",onos-classic.image.tag=" + split[1] + " "
       }
       def localCharts = false
       if (branch != "master") {