Refactor: remove code duplication for openstacktelemetry app

Change-Id: I3a97bc22e8a49ef6184876875351ebba8111e25c
diff --git a/apps/openstacktelemetry/app/src/main/java/org/onosproject/openstacktelemetry/util/OpenstackTelemetryUtil.java b/apps/openstacktelemetry/app/src/main/java/org/onosproject/openstacktelemetry/util/OpenstackTelemetryUtil.java
index abc4e97..a957369 100644
--- a/apps/openstacktelemetry/app/src/main/java/org/onosproject/openstacktelemetry/util/OpenstackTelemetryUtil.java
+++ b/apps/openstacktelemetry/app/src/main/java/org/onosproject/openstacktelemetry/util/OpenstackTelemetryUtil.java
@@ -17,6 +17,8 @@
 
 import com.google.common.base.Strings;
 import org.onosproject.cfg.ConfigProperty;
+import org.onosproject.openstacktelemetry.api.TelemetryAdminService;
+import org.onosproject.openstacktelemetry.api.config.TelemetryConfig;
 
 import java.util.Dictionary;
 import java.util.Optional;
@@ -68,4 +70,27 @@
 
         return property.map(ConfigProperty::asBoolean).orElse(false);
     }
+
+    /**
+     * Initializes the telemetry service due tue configuration changes.
+     *
+     *
+     * @param adminService  telemetry admin service
+     * @param config        telemetry configuration
+     * @param enable        service enable flag
+     */
+    public static void initTelemetryService(TelemetryAdminService adminService,
+                                            TelemetryConfig config, boolean enable) {
+        if (enable) {
+            if (adminService.isRunning()) {
+                adminService.restart(config);
+            } else {
+                adminService.start(config);
+            }
+        } else {
+            if (adminService.isRunning()) {
+                adminService.stop();
+            }
+        }
+    }
 }