Fix crash when editing an application period (#117)

Fixes #68

## How to test
1. Log in as admin
2. Go to "Match / Application periods"
3. Click the edit icon (6th column)
4. Click "Save"

Co-authored-by: Nico Athanassiadis <nico@dsv.su.se>
Reviewed-on: #117
Reviewed-by: Nico Athanassiadis <nico@dsv.su.se>
Co-authored-by: Andreas Svanberg <andreass@dsv.su.se>
Co-committed-by: Andreas Svanberg <andreass@dsv.su.se>

core/src/main/java/se/su/dsv/scipro/match/ApplicationPeriod.java

@@ -176,18 +176,16 @@ public class ApplicationPeriod extends DomainObject {
         return Collections.unmodifiableSet(answerSet);
     }
 
-    public void setProjectTypes(Iterable<ProjectType> projectTypes) {
-        this.projectTypes.clear();
+    public void setProjectTypes(Set<ProjectType> projectTypes) {
+        this.projectTypes.removeIf(appt -> !projectTypes.contains(appt.getProjectType()));
         for (ProjectType pt : projectTypes) {
-            this.projectTypes.add(new ApplicationPeriodProjectType(this, pt));
+            if (this.projectTypes.stream().noneMatch(appt -> appt.getProjectType().equals(pt))) {
+                addProjectType(pt);
+            }
         }
     }
 
     public void addProjectType(ProjectType projectType) {
         this.projectTypes.add(new ApplicationPeriodProjectType(this, projectType));
     }
-
-    public void removeProjectType(ProjectType projectType) {
-        this.projectTypes.removeIf(next -> next.getProjectType().equals(projectType));
-    }
 }

view/src/main/java/se/su/dsv/scipro/applicationperiod/AdminApplicationPeriodsPanel.java

@@ -123,13 +123,7 @@ public class AdminApplicationPeriodsPanel extends Panel {
                     item.add(
                         new DisplayMultiplesPanel<>(
                             s,
-                            new ListAdapterModel<>(
-                                LambdaModel.of(
-                                    iModel,
-                                    ApplicationPeriod::getProjectTypes,
-                                    ApplicationPeriod::setProjectTypes
-                                )
-                            )
+                            new ListAdapterModel<>(iModel.map(ApplicationPeriod::getProjectTypes))
                         ) {
                             @Override
                             public Component getComponent(String componentId, IModel<ProjectType> t) {

view/src/main/java/se/su/dsv/scipro/datatables/target/AddTargetLinkPanel.java

@@ -22,12 +22,7 @@ public class AddTargetLinkPanel extends Panel {
     public AddTargetLinkPanel(String id, final IModel<ApplicationPeriod> model) {
         super(id, model);
         add(
-            new ListView<>(
-                "list",
-                new ListAdapterModel<>(
-                    LambdaModel.of(model, ApplicationPeriod::getProjectTypes, ApplicationPeriod::setProjectTypes)
-                )
-            ) {
+            new ListView<>("list", new ListAdapterModel<>(model.map(ApplicationPeriod::getProjectTypes))) {
                 @Override
                 protected void populateItem(ListItem<ProjectType> item) {
                     item.add(new Label("pc", item.getModelObject().getName()));

view/src/main/java/se/su/dsv/scipro/projectpartner/ProjectPartnerPage.java

@@ -76,13 +76,7 @@ public class ProjectPartnerPage extends AbstractIdeaProjectPage implements MenuH
             }
         );
         final IModel<? extends List<ProjectType>> matchableTypes = getMatchableTypes(
-            new ListAdapterModel<>(
-                LambdaModel.of(
-                    applicationPeriod,
-                    ApplicationPeriod::getProjectTypes,
-                    ApplicationPeriod::setProjectTypes
-                )
-            )
+            new ListAdapterModel<>(applicationPeriod.map(ApplicationPeriod::getProjectTypes))
         );
         panelContainer.add(
             new ListView<>("ads", matchableTypes) {