[ONOS-6016] Enhance IntentInstaller for FlowObjective

Note:
Provide order of objective context (for remove only)
Handling objective errors in intent installer

Change-Id: I50bb9d7a17a0ae71d22ba035cd5bc80f485ec45a
diff --git a/core/api/src/main/java/org/onosproject/net/flowobjective/ObjectiveError.java b/core/api/src/main/java/org/onosproject/net/flowobjective/ObjectiveError.java
index bd51902..e00f2b8 100644
--- a/core/api/src/main/java/org/onosproject/net/flowobjective/ObjectiveError.java
+++ b/core/api/src/main/java/org/onosproject/net/flowobjective/ObjectiveError.java
@@ -66,5 +66,20 @@
     /**
      * An unknown error occurred.
      */
-    UNKNOWN
+    UNKNOWN,
+
+    /**
+     * Flow/Group installation retry threshold exceeded.
+     */
+    INSTALLATIONTHRESHOLDEXCEEDED,
+
+    /**
+     * Installation timeout.
+     */
+    INSTALLATIONTIMEOUT,
+
+    /**
+     * Group already exists.
+     */
+    GROUPEXISTS
 }