ScheduleManager: отложенное выполнение задач

src/main/java/ghast/scheduler/JavaScheduleTask.java

@@ -3,19 +3,31 @@ package ghast.scheduler;
 import lombok.RequiredArgsConstructor;
 
 import java.util.concurrent.Future;
+import java.util.function.Supplier;
 
 @RequiredArgsConstructor
 public class JavaScheduleTask implements ScheduleTask {
 
-	private final Future<?> future;
+	private final Supplier<Future<?>> generator;
+	private Future<?> future;
+
+	@Override
+	public void start() {
+		if (future == null || future.isDone()) {
+			future = generator.get();
+		}
+	}
 
 	@Override
 	public boolean isCanceled() {
-		return future.isCancelled();
+		return future == null || future.isCancelled();
 	}
 
 	@Override
 	public void cancel() {
-		future.cancel(true);
+		if (future != null) {
+			future.cancel(true);
+			future = null;
+		}
 	}
 }