Remove soft fail for registering an empty property set

- removed soft fail
- fixed property reference in DriverRegistryManager that had been refactored out
- fixed property references in FlowObjectiveManager so that property name and
  variable name match

Change-Id: I1324c0553e0f6945087b29794f0a06ae6dd8ab10
diff --git a/core/net/src/main/java/org/onosproject/net/flowobjective/impl/FlowObjectiveManager.java b/core/net/src/main/java/org/onosproject/net/flowobjective/impl/FlowObjectiveManager.java
index 58cb215..45e2e95 100644
--- a/core/net/src/main/java/org/onosproject/net/flowobjective/impl/FlowObjectiveManager.java
+++ b/core/net/src/main/java/org/onosproject/net/flowobjective/impl/FlowObjectiveManager.java
@@ -94,7 +94,6 @@
 
     private static final String WORKER_PATTERN = "objective-installer-%d";
     private static final String GROUP_THREAD_NAME = "onos/objective-installer";
-    private static final String NUM_THREAD = "numThreads";
 
     private final Logger log = LoggerFactory.getLogger(getClass());
 
@@ -154,7 +153,7 @@
 
     @Activate
     protected void activate() {
-        cfgService.registerProperties(getClass());
+        cfgService.registerProperties(FlowObjectiveManager.class);
         executorService = newFixedThreadPool(numThreads,
                                              groupedThreads(GROUP_THREAD_NAME, WORKER_PATTERN, log));
         flowObjectiveStore.setDelegate(delegate);
@@ -179,7 +178,7 @@
     @Modified
     protected void modified(ComponentContext context) {
         String propertyValue =
-                Tools.get(context.getProperties(), NUM_THREAD);
+                Tools.get(context.getProperties(), FOM_NUM_THREADS);
         int newNumThreads = isNullOrEmpty(propertyValue) ? numThreads : Integer.parseInt(propertyValue);
 
         if (newNumThreads != numThreads && newNumThreads > 0) {