poolmanager: make RendezvousPoolManagerHandler#backendFor private

Motivation:
- never used by other components
- exposes implementation details

Modification:
Make RendezvousPoolManagerHandler#backendFor private. Remove unused
method.

Result:
less unused code + better encapsulation.

Acked-by: Lea Morschel
Acked-by: Paul Millar
Target: master
Require-book: no
Require-notes: no

modules/dcache/src/main/java/org/dcache/poolmanager/RendezvousPoolManagerHandler.java

@@ -69,7 +69,7 @@ public RendezvousPoolManagerHandler(CellAddressCore serviceAddress, List<CellAdd
         this.backends = backends;
     }
 
-    public CellAddressCore backendFor(PnfsId pnfsId)
+    private CellAddressCore backendFor(PnfsId pnfsId)
     {
         Iterator<CellAddressCore> iterator = backends.iterator();
         CellAddressCore address = iterator.next();
@@ -85,19 +85,14 @@ public CellAddressCore backendFor(PnfsId pnfsId)
         return address;
     }
 
-    public CellAddressCore backendFor(PoolManagerMessage msg)
+    private CellAddressCore backendFor(PoolManagerMessage msg)
     {
         if (msg instanceof PoolMgrGetPoolMsg) {
             return backendFor(((PoolMgrGetPoolMsg) msg).getFileAttributes().getPnfsId());
         }
         return serviceAddress;
     }
 
-    public CellAddressCore backendFor(PoolIoFileMessage msg)
-    {
-        return backendFor(msg.getFileAttributes().getPnfsId());
-    }
-
     private static int hash(PnfsId pnfsId, CellAddressCore address)
     {
         return Hashing.murmur3_32().newHasher()