Move all action updates from EDT to BGT

CHANGE-NOTES.md

@@ -1,6 +1,7 @@
 # Changelog
 
 ## v4.0.3
+- Fixed: all `com.intellij.diagnostic.PluginException: ... ms to call on EDT ...#update@...` errors, hopefully for good (reported by @itxshakil)
 
 ## v4.0.2
 - Fixed: more `com.intellij.diagnostic.PluginException: ... ms to call on EDT ...#update@...` errors (reported by @itxshakil)

frontend/actions/src/main/java/com/virtuslab/gitmachete/frontend/actions/base/BaseProjectDependentAction.java

@@ -22,17 +22,14 @@
 @ExtensionMethod({GitMacheteBundle.class})
 public abstract class BaseProjectDependentAction extends DumbAwareAction implements IWithLogger {
 
-  // Let's eagerly load these classes so that they do NOT end up loaded from an action `update` method.
-  // See issues #1692, #1694, #1713.
-  static {
-    @SuppressWarnings("nullness:argument") val dummyService = new SideEffectingActionTrackingService(null);
-
-    @SuppressWarnings("nullness:argument") val dummyId = new SideEffectingActionTrackingService.SideEffectiveActionId(null);
-  }
-
   @Override
   public final ActionUpdateThread getActionUpdateThread() {
-    return ActionUpdateThread.EDT;
+    // This is questionable, as update()/onUpdate() methods are supposed to be `@UIEffect` (able to touch UI directly).
+    // Still, using ActionUpdateThread.EDT here led to issues like #1692, #1694, #1713:
+    // update() taking more than 300ms on UI thread due to loading classes and other surprisingly heavyweight operations.
+    // Let's instead use BGT... somehow this doesn't lead to errors so far
+    // (but it might cause race conditions at some point (?)).
+    return ActionUpdateThread.BGT;
   }
 
   @UIEffect

frontend/ui/impl/src/main/java/com/virtuslab/gitmachete/frontend/ui/impl/gitrepositoryselection/GitRepositoryComboBox.java

@@ -5,6 +5,7 @@
 
 import com.intellij.dvcs.DvcsUtil;
 import com.intellij.dvcs.repo.VcsRepositoryManager;
+import com.intellij.dvcs.repo.VcsRepositoryMappingListener;
 import com.intellij.openapi.Disposable;
 import com.intellij.openapi.application.ModalityState;
 import com.intellij.openapi.project.Project;
@@ -46,7 +47,7 @@ public GitRepositoryComboBox(Project project) {
 
     val messageBusConnection = project.getMessageBus().connect();
     messageBusConnection
-        .subscribe(VcsRepositoryManager.VCS_REPOSITORY_MAPPING_UPDATED, () -> {
+        .<VcsRepositoryMappingListener>subscribe(VcsRepositoryManager.VCS_REPOSITORY_MAPPING_UPDATED, () -> {
           LOG.debug("Git repository mappings changed");
           ModalityUiUtil.invokeLaterIfNeeded(ModalityState.NON_MODAL, () -> updateRepositories());
         });