Fix nullPointerException

Fix nullPointerException by changing return values of attributesProvided
and attributesRequired from null to empty Set.

Issue-ID: POLICY-55
Change-Id: I9516a9bcad591cc582834cb49fa54e58a1f45a47
Signed-off-by: Temoc Rodriguez <cr056n@att.com>

diff --git a/controlloop/common/guard/src/main/java/org/onap/policy/guard/PIPEngineGetHistory.java b/controlloop/common/guard/src/main/java/org/onap/policy/guard/PIPEngineGetHistory.java
index 0ec0098..3e93bd7 100644 (file)
--- a/controlloop/common/guard/src/main/java/org/onap/policy/guard/PIPEngineGetHistory.java
+++ b/controlloop/common/guard/src/main/java/org/onap/policy/guard/PIPEngineGetHistory.java
@@ -23,6 +23,7 @@ package org.onap.policy.guard;
 import java.math.BigInteger;
 import java.sql.Timestamp;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.Date;
 import java.util.HashSet;
 import java.util.Iterator;
@@ -112,13 +113,13 @@ public class PIPEngineGetHistory extends StdConfigurableEngine{
        @Override
        public Collection<PIPRequest> attributesRequired() {
                // TODO Auto-generated method stub
-               return null;
+           return Collections.emptySet();
        }
 
        @Override
        public Collection<PIPRequest> attributesProvided() {
                // TODO Auto-generated method stub
-               return null;
+           return Collections.emptySet();
        }
 
        @Override