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/dms/src/main/java/sample/dms/AbstractElement.java

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

samples/xml/dms/src/main/java/sample/dms/DataSourcePopulator.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package sample.dms;
 
 import javax.sql.DataSource;

samples/xml/dms/src/main/java/sample/dms/Directory.java

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

samples/xml/dms/src/main/java/sample/dms/DocumentDao.java

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

samples/xml/dms/src/main/java/sample/dms/DocumentDaoImpl.java

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

samples/xml/dms/src/main/java/sample/dms/File.java

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

samples/xml/dms/src/main/java/sample/dms/secured/SecureDataSourcePopulator.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package sample.dms.secured;
 
 import javax.sql.DataSource;

samples/xml/dms/src/main/java/sample/dms/secured/SecureDocumentDao.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package sample.dms.secured;
 
 import sample.dms.DocumentDao;

samples/xml/dms/src/main/java/sample/dms/secured/SecureDocumentDaoImpl.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package sample.dms.secured;
 
 import org.springframework.security.acls.domain.BasePermission;

samples/xml/dms/src/test/java/sample/DmsIntegrationTests.java

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

samples/xml/dms/src/test/java/sample/SecureDmsIntegrationTests.java

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