Fix PMD errors in REST API framework

Also refactored error catalog to get rid of a useless wrapper
class.

Change-Id: I0d4b190703b85cdea91da00e7f238538e7c115ec
diff --git a/src/main/java/net/onrc/onos/api/rest/RestErrorCode.java b/src/main/java/net/onrc/onos/api/rest/RestErrorCode.java
new file mode 100644
index 0000000..1ff9186
--- /dev/null
+++ b/src/main/java/net/onrc/onos/api/rest/RestErrorCode.java
@@ -0,0 +1,21 @@
+package net.onrc.onos.api.rest;
+
+/**
+ * Enumeration of the ONOS defined error codes.
+ */
+public enum RestErrorCode {
+
+    // TODO: These are made up just for testing purposes.
+
+    /** Intent not found. */
+    INTENT_NOT_FOUND,
+
+    /** Intent already exists. */
+    INTENT_ALREADY_EXISTS,
+
+    /** No path available for the Intent. */
+    INTENT_NO_PATH,
+
+    /** An object specified for an intent is invalid (parsing error). */
+    INTENT_INVALID
+}