Use Collection#forEach() instead of Stream#forEach() for simplicity

Change-Id: I0a1aea4bdb5d305c50273e6ff749fe71bd2a295a
diff --git a/apps/openstacknetworking/switching/src/main/java/org/onosproject/openstacknetworking/switching/OpenstackSwitchingArpHandler.java b/apps/openstacknetworking/switching/src/main/java/org/onosproject/openstacknetworking/switching/OpenstackSwitchingArpHandler.java
index c35371f..d70524c 100644
--- a/apps/openstacknetworking/switching/src/main/java/org/onosproject/openstacknetworking/switching/OpenstackSwitchingArpHandler.java
+++ b/apps/openstacknetworking/switching/src/main/java/org/onosproject/openstacknetworking/switching/OpenstackSwitchingArpHandler.java
@@ -194,8 +194,7 @@
             log.warn("Failed to get OpenStack network for {}", host);
             return;
         }
-        osNet.subnets().stream()
-                .forEach(subnet -> gateways.add(Ip4Address.valueOf(subnet.gatewayIp())));
+        osNet.subnets().forEach(subnet -> gateways.add(Ip4Address.valueOf(subnet.gatewayIp())));
     }
 
     @Override