Do not override configured hosts

- When multiple host providers add the same host, the configured one will always win
- A provider can only remove a host provided by itself

Change-Id: I38d95cceed6f36c71b8417ce6812bbd5add10e57
diff --git a/core/store/dist/src/main/java/org/onosproject/store/host/impl/DistributedHostStore.java b/core/store/dist/src/main/java/org/onosproject/store/host/impl/DistributedHostStore.java
index 356df9c..bfb60c7 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/host/impl/DistributedHostStore.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/host/impl/DistributedHostStore.java
@@ -119,6 +119,11 @@
             return true;
         }
 
+        // Avoid overriding configured hosts
+        if (existingHost.configured()) {
+            return false;
+        }
+
         if (!Objects.equals(existingHost.providerId(), providerId) ||
                 !Objects.equals(existingHost.mac(), hostDescription.hwAddress()) ||
                 !Objects.equals(existingHost.vlan(), hostDescription.vlan()) ||