change type to private

Author: sakthivelmanii

google-cloud-spanner/src/test/java/com/google/cloud/spanner/RetryOnInvalidatedSessionTest.java

@@ -82,7 +82,7 @@ public Long apply(StructReader input) {
   private static final ToLongTransformer TO_LONG = new ToLongTransformer();
 
   @Parameter(0)
-  public boolean failOnInvalidatedSession;
+  public volatile boolean failOnInvalidatedSession;
 
   @Rule
   public TestRule watcher =
@@ -177,8 +177,8 @@ public static Collection<Object[]> data() {
   private static Server server;
   private static LocalChannelProvider channelProvider;
   private static SpannerClient spannerClient;
-  private static Spanner spanner;
-  private static DatabaseClient client;
+  private Spanner spanner;
+  private DatabaseClient client;
   private static ExecutorService executor;
 
   @BeforeClass