SGF-458 - Enable resolution of GemFire's DistributedSystem and System properties to be overridden in PoolFactoryBean.

(cherry picked from commit 10fadc0d9a92d007a7bff85045c5169f2d8797f7)
Signed-off-by: John Blum <jblum@pivotal.io>

src/test/java/org/springframework/data/gemfire/client/PoolUsingLocatorsAndServersPropertyPlaceholdersTest.java

@@ -155,7 +155,7 @@ public class PoolUsingLocatorsAndServersPropertyPlaceholdersTest {
 		}
 
 		@Override
-		void resolveDistributedSystem() {
+		protected void resolveDistributedSystem() {
 		}
 	}