Add single, constant, class member reference to an instance of IdentityHashCodeComparator.

spring-data-geode-test/src/main/java/org/springframework/data/gemfire/tests/util/IdentityHashCodeComparator.java

@@ -27,6 +27,8 @@ import java.util.Comparator;
 @SuppressWarnings("unused")
 public class IdentityHashCodeComparator implements Comparator<Object> {
 
+	public static final IdentityHashCodeComparator INSTANCE = new IdentityHashCodeComparator();
+
 	@Override
 	public int compare(Object objectOne, Object objectTwo) {