fix sonar for m2/base - 2

- unused import
- Hide Utility Class Constructor : Utility classes
  should not have a public or default constructor

Issue-ID: POLICY-2616
Change-Id: I338a739b6e9fb5f4b47898566362b8a87201dae3
Signed-off-by: Taka Cho <takamune.cho@att.com>
diff --git a/controlloop/m2/base/src/main/java/org/onap/policy/m2/base/Util.java b/controlloop/m2/base/src/main/java/org/onap/policy/m2/base/Util.java
index 8e6d98b..5347b5c 100644
--- a/controlloop/m2/base/src/main/java/org/onap/policy/m2/base/Util.java
+++ b/controlloop/m2/base/src/main/java/org/onap/policy/m2/base/Util.java
@@ -20,10 +20,6 @@
 
 package org.onap.policy.m2.base;
 
-import java.util.List;
-
-import org.onap.policy.common.endpoints.event.comm.TopicEndpointManager;
-import org.onap.policy.common.endpoints.event.comm.TopicSink;
 import org.onap.policy.drools.core.PolicyContainer;
 import org.onap.policy.drools.core.PolicySession;
 import org.onap.policy.drools.system.PolicyController;
@@ -34,6 +30,11 @@
  * This class contains static utility methods.
  */
 public class Util {
+    // Add a private Util to hide the implicit public one.
+    private Util() {
+        //not called
+    }
+
     /**
      * Find the PolicyController associated with the specified PolicySession.
      *