Added milestone picker logic which relies on text input. Clicking of …

…milestones is not working yet. Modified MilestonePickerDialog return type to Pair since we have to know both the button pressed and milestone selection result, which fixes removing milestone when Cancel is pressed.

src/main/java/ui/components/pickers/MilestonePicker.java

@@ -4,7 +4,9 @@
 import backend.resource.TurboMilestone;
 import backend.resource.TurboUser;
 import javafx.application.Platform;
+import javafx.scene.control.ButtonType;
 import javafx.stage.Stage;
+import javafx.util.Pair;
 import ui.UI;
 import undo.actions.ChangeLabelsAction;
 import undo.actions.ChangeMilestoneAction;
@@ -26,10 +28,13 @@ public MilestonePicker(UI ui, Stage mainStage) {
     private void showMilestonePicker(TurboIssue issue) {
         List<TurboMilestone> milestoneList = ui.logic.getRepo(issue.getRepoId()).getMilestones();
         MilestonePickerDialog dialog = new MilestonePickerDialog(stage, issue, milestoneList);
-        Optional<Integer> assignedMilestone = dialog.showAndWait();;
+        Optional<Pair<ButtonType, Integer>> assignedMilestone = dialog.showAndWait();
 
-        if (!issue.getMilestone().equals(assignedMilestone)) {
-            ui.undoController.addAction(issue, new ChangeMilestoneAction(ui.logic, issue.getMilestone(), assignedMilestone));
+        if (!assignedMilestone.isPresent()) return;
+        if (assignedMilestone.get().getKey().equals(ButtonType.CANCEL)) return;
+        if (!issue.getMilestone().equals(assignedMilestone.get().getValue())) {
+            ui.undoController.addAction(issue, new ChangeMilestoneAction(ui.logic, issue.getMilestone(),
+                    Optional.of(assignedMilestone.get().getValue())));
         }
     }