Merge branch 'fix-checkstyle-pmd-issues'

This closes #65

src/main/java/org/apache/commons/collections4/SetUtils.java

@@ -97,7 +97,7 @@ public class SetUtils {
             return set;
         }
     }
-    
+
     /**
      * An empty unmodifiable sorted set.
      * This is not provided in the JDK.

src/main/java/org/apache/commons/collections4/list/SetUniqueList.java

@@ -16,7 +16,6 @@
  */
 package org.apache.commons.collections4.list;
 
-import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
 import java.util.ArrayList;
 import java.util.Collection;

src/main/java/org/apache/commons/collections4/map/AbstractReferenceMap.java

@@ -111,7 +111,7 @@ public abstract class AbstractReferenceMap<K, V> extends AbstractHashedMap<K, V>
             }
         }
 
-        private ReferenceStrength(final int value) {
+        ReferenceStrength(final int value) {
             this.value = value;
         }