fix(DepositDocSerializer): avoid NullPointerException when checking if a collaborator exists

AoU-Model/src/main/java/ch/unige/aou/model/xml/deposit/v2_4/serializer/DepositDocSerializer.java

@@ -9,12 +9,12 @@
  * it under the terms of the GNU General Public License as
  * published by the Free Software Foundation, either version 2 of the
  * License, or (at your option) any later version.
- * 
+ *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
- * 
+ *
  * You should have received a copy of the GNU General Public
  * License along with this program.  If not, see
  * <http://www.gnu.org/licenses/gpl-2.0.html>.
@@ -79,7 +79,8 @@ public class DepositDocSerializer extends StdSerializer<DepositDoc> {
     List<Serializable> contributorsOrCollaborations = null;
     if (value.getContributors() != null) {
       contributorsOrCollaborations = value.getContributors().getContributorOrCollaboration();
-      isCollaboration = contributorsOrCollaborations.stream().anyMatch(serializable -> serializable instanceof Contributor && ((Contributor)serializable).getRole().equals(COLLABORATOR));
+      isCollaboration = contributorsOrCollaborations.stream()
+              .anyMatch(s -> s instanceof Contributor contributor && COLLABORATOR.equals(contributor.getRole()));
     }
     contributorsFormStep.put("isCollaboration", isCollaboration);
     contributorsFormStep.put("academicStructures", value.getAcademicStructures());