add bridge configuration at Arista Switch driver
For Arista switch, the following code is required
because the port to be used as OpenFlow bridge should be added.

Change-Id: Id73560b9c9592838ba91329ef652742fb1beb65b
diff --git a/core/api/src/main/java/org/onosproject/net/behaviour/BridgeConfig.java b/core/api/src/main/java/org/onosproject/net/behaviour/BridgeConfig.java
index e9ee007..d155a14 100644
--- a/core/api/src/main/java/org/onosproject/net/behaviour/BridgeConfig.java
+++ b/core/api/src/main/java/org/onosproject/net/behaviour/BridgeConfig.java
@@ -15,6 +15,7 @@
  */
 package org.onosproject.net.behaviour;
 
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 import java.util.Set;
@@ -59,6 +60,19 @@
     void addPort(BridgeName bridgeName, String portName);
 
     /**
+     * Adds ports to a given bridge.
+     *
+     * @param bridgeName bridge name
+     * @param portNames list port name
+     */
+    default void addPorts(BridgeName bridgeName, List<String> portNames) {
+        List<String> portsList = new ArrayList<>();
+        for (String portName : portNames) {
+                portsList.add(portName);
+        }
+    }
+
+    /**
      * Removes a port from a given bridge.
      *
      * @param bridgeName bridge name
diff --git a/drivers/arista/src/main/java/org/onosproject/drivers/arista/BridgeConfigAristaImpl.java b/drivers/arista/src/main/java/org/onosproject/drivers/arista/BridgeConfigAristaImpl.java
index ce64459..42f08f7 100644
--- a/drivers/arista/src/main/java/org/onosproject/drivers/arista/BridgeConfigAristaImpl.java
+++ b/drivers/arista/src/main/java/org/onosproject/drivers/arista/BridgeConfigAristaImpl.java
@@ -72,6 +72,18 @@
     }
 
     @Override
+    public void addPorts(BridgeName bridgeName, List<String> portNames) {
+        List<String> cmds = new ArrayList<>();
+        cmds.add(CONFIGURE_TERMINAL);
+        cmds.add(OPENFLOW_CMD);
+        for (String portName : portNames) {
+            cmds.add(String.format(BIND_CMD, portName));
+        }
+
+        AristaUtils.getWithChecking(handler(), cmds);
+    }
+
+    @Override
     public void deletePort(BridgeName bridgeName, String portName) {
         List<String> cmds = new ArrayList<>();
         cmds.add(CONFIGURE_TERMINAL);