Add whitespace after copyright header

Add an additional lines after the copyright header and before the
`package` declaration. This aligns with the style used by Spring
Framework.

Issue gh-8945

samples/xml/tutorial/src/main/java/bigbank/Account.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package bigbank;
 
 /**

samples/xml/tutorial/src/main/java/bigbank/BankDao.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package bigbank;
 
 public interface BankDao {

samples/xml/tutorial/src/main/java/bigbank/BankDaoStub.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package bigbank;
 
 import java.util.HashMap;

samples/xml/tutorial/src/main/java/bigbank/BankService.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package bigbank;
 
 import org.springframework.security.access.prepost.PreAuthorize;

samples/xml/tutorial/src/main/java/bigbank/BankServiceImpl.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package bigbank;
 
 import org.springframework.util.Assert;

samples/xml/tutorial/src/main/java/bigbank/SeedData.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package bigbank;
 
 import org.springframework.beans.factory.InitializingBean;

samples/xml/tutorial/src/main/java/bigbank/web/ListAccounts.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package bigbank.web;
 
 import javax.servlet.http.HttpServletRequest;

samples/xml/tutorial/src/main/java/bigbank/web/PostAccounts.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package bigbank.web;
 
 import javax.servlet.http.HttpServletRequest;