ONOS-3460 - Link provider that enforces strict configuration

This provider uses the "links" configuration of the network
config and only allows discovery of links that are in
the config.

Refactoring will be done in a subsequent patch set - the DiscoveryContext and
LinkDiscovery classes are duplicates, they need to be refactored so the
LLDP provider and the Network Config provider can share them.

Change-Id: I4de12fc1c4ffa05e3cac7767b8a31f48ba379f6c
diff --git a/utils/misc/src/main/java/org/onlab/packet/ONOSLLDP.java b/utils/misc/src/main/java/org/onlab/packet/ONOSLLDP.java
index 78a6ad3..f025521 100644
--- a/utils/misc/src/main/java/org/onlab/packet/ONOSLLDP.java
+++ b/utils/misc/src/main/java/org/onlab/packet/ONOSLLDP.java
@@ -71,7 +71,7 @@
     private final byte[] ttlValue = new byte[] {0, 0x78};
 
     // Only needs to be accessed from LinkProbeFactory.
-    protected ONOSLLDP(byte ... subtype) {
+    public ONOSLLDP(byte ... subtype) {
         super();
         for (byte st : subtype) {
             opttlvs.put(st, new LLDPOrganizationalTLV());