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/javaconfig/data/src/main/java/samples/DataConfig.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package samples;
 
 import org.springframework.context.annotation.Bean;

samples/javaconfig/data/src/main/java/samples/data/Message.java

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

samples/javaconfig/data/src/main/java/samples/data/MessageRepository.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package samples.data;
 
 import org.springframework.data.jpa.repository.JpaRepository;

samples/javaconfig/data/src/main/java/samples/data/SecurityMessageRepository.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package samples.data;
 
 import org.springframework.data.jpa.repository.Query;

samples/javaconfig/data/src/main/java/samples/data/User.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package samples.data;
 
 import javax.persistence.Entity;

samples/javaconfig/data/src/test/java/samples/data/SecurityMessageRepositoryTests.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package samples.data;
 
 import org.junit.After;