Implement synchronous execution for BukkitSchedulerAdapter;

Add javadoc for SchedulerAdapter interface;

(cherry picked from commit 919a249eb5)

worldguard-bukkit/src/main/java/com/sk89q/worldguard/bukkit/scheduler/BukkitSchedulerAdapter.java

@@ -27,6 +27,7 @@ import org.bukkit.scheduler.BukkitScheduler;
 public class BukkitSchedulerAdapter implements SchedulerAdapter {
 
     private final Plugin plugin;
+    @SuppressWarnings("deprecation")
     private final BukkitScheduler scheduler;
 
     public BukkitSchedulerAdapter(final Plugin plugin) {
@@ -34,33 +35,28 @@ public class BukkitSchedulerAdapter implements SchedulerAdapter {
         this.scheduler = plugin.getServer().getScheduler();
     }
 
-    @Override
-    public void runAsync(final Runnable runnable) {
-        scheduler.runTaskAsynchronously(plugin, runnable);
-    }
-
     @Override
     public void runAsyncRate(Runnable runnable, long delay, long period) {
         scheduler.runTaskTimerAsynchronously(plugin, runnable, delay, period);
     }
 
     @Override
-    public void runAtEntity(Entity entity, Runnable runnable) {
-
+    public void executeAtEntity(Entity entity, Runnable runnable) {
+        scheduler.runTask(plugin, runnable);
     }
 
     @Override
-    public void runAtEntityLater(final Entity entity, final Runnable runnable, final long delay) {
+    public void runAtEntityDelayed(final Entity entity, final Runnable runnable, final long delay) {
         scheduler.runTaskLater(plugin, runnable, delay);
     }
 
     @Override
-    public void runAtRegion(Location location, Runnable runnable) {
-
+    public void executeAtRegion(Location location, Runnable runnable) {
+        scheduler.runTask(plugin, runnable);
     }
 
     @Override
     public void cancelTasks() {
-
+        scheduler.cancelTasks(plugin);
     }
 }

worldguard-bukkit/src/main/java/com/sk89q/worldguard/bukkit/scheduler/FoliaSchedulerAdapter.java

@@ -53,28 +53,23 @@ public class FoliaSchedulerAdapter implements SchedulerAdapter {
         }
     }
 
-    @Override
-    public void runAsync(final Runnable runnable) {
-        asyncScheduler.runNow(plugin, task -> runnable.run());
-    }
-
     @Override
     public void runAsyncRate(final Runnable runnable, final long delay, final long period) {
         asyncScheduler.runAtFixedRate(plugin, task -> runnable.run(), delay * 50, period * 50, TimeUnit.MILLISECONDS);
     }
 
     @Override
-    public void runAtEntity(final Entity entity, final Runnable runnable) {
+    public void executeAtEntity(final Entity entity, final Runnable runnable) {
         entity.getScheduler().run(plugin, task -> runnable.run(), null);
     }
 
     @Override
-    public void runAtEntityLater(final Entity entity, final Runnable runnable, final long delay) {
+    public void runAtEntityDelayed(final Entity entity, final Runnable runnable, final long delay) {
         entity.getScheduler().execute(plugin, runnable, null, delay);
     }
 
     @Override
-    public void runAtRegion(final Location location, final Runnable runnable) {
+    public void executeAtRegion(final Location location, final Runnable runnable) {
         regionScheduler.execute(plugin, location, runnable);
     }
 

worldguard-bukkit/src/main/java/com/sk89q/worldguard/bukkit/scheduler/SchedulerAdapter.java

@@ -24,15 +24,59 @@ import org.bukkit.entity.Entity;
 
 public interface SchedulerAdapter {
 
-  void runAsync(Runnable runnable);
+    /**
+     * Schedules the specified task to be executed asynchronously after the delay has passed,
+     * and then periodically executed with the specified period.
+     *
+     * @param runnable The task to execute.
+     * @param delay    The time delay to pass before the task should be executed.
+     * @param period   The time between task executions after the first execution of the task.
+     */
+    void runAsyncRate(Runnable runnable, long delay, long period);
 
-  void runAsyncRate(Runnable runnable, long delay, long period);
+    /**
+     * Schedules a task. If the task failed to schedule because the scheduler is retired (entity removed),
+     * then returns {@code false}. Otherwise, either the run callback will be invoked after the specified delay,
+     * or the retired callback will be invoked if the scheduler is retired.
+     * Note that the retired callback is invoked in critical code, so it should not attempt to remove the entity,
+     * remove other entities, load chunks, load worlds, modify ticket levels, etc.
+     *
+     * <p>
+     * It is guaranteed that the task and retired callback are invoked on the region which owns the entity.
+     * </p>
+     *
+     * @param entity   The entity relative to which the scheduler is obtained.
+     * @param runnable The task to execute.
+     */
+    void executeAtEntity(Entity entity, Runnable runnable);
 
-  void runAtEntity(Entity entity, Runnable runnable);
+    /**
+     * Schedules a task with the given delay. If the task failed to schedule because the scheduler is retired (entity removed),
+     * then returns {@code false}. Otherwise, either the run callback will be invoked after the specified delay,
+     * or the retired callback will be invoked if the scheduler is retired.
+     * Note that the retired callback is invoked in critical code, so it should not attempt to remove the entity,
+     * remove other entities, load chunks, load worlds, modify ticket levels, etc.
+     *
+     * <p>
+     * It is guaranteed that the task and retired callback are invoked on the region which owns the entity.
+     * </p>
+     *
+     * @param entity   The entity relative to which the scheduler is obtained.
+     * @param runnable The task to execute.
+     * @param delay    The time delay to pass before the task should be executed, in ticks.
+     */
+    void runAtEntityDelayed(Entity entity, Runnable runnable, long delay);
 
-  void runAtEntityLater(Entity entity, Runnable runnable, long delay);
+    /**
+     * Schedules a task to be executed on the region which owns the location.
+     *
+     * @param location The location at which the region executing should own.
+     * @param runnable The task to execute.
+     */
+    void executeAtRegion(Location location, Runnable runnable);
 
-  void runAtRegion(Location location, Runnable runnable);
-
-  void cancelTasks();
+    /**
+     * Attempts to cancel all tasks scheduled by the plugin.
+     */
+    void cancelTasks();
 }