fix: recurring tasks get correct default priority without data (#604)

db-scheduler/src/main/java/com/github/kagkarlsson/scheduler/task/AbstractTask.java

@@ -45,7 +45,7 @@ public Class<T> getDataClass() {
 
   @Override
   public TaskInstance<T> instance(String id) {
-    return instanceBuilder(id).build();
+    return instanceBuilder(id).priority(getDefaultPriority()).build();
   }
 
   @Override

db-scheduler/src/test/java/com/github/kagkarlsson/scheduler/task/AbstractTaskTest.java

@@ -0,0 +1,30 @@
+package com.github.kagkarlsson.scheduler.task;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import com.github.kagkarlsson.scheduler.task.helper.RecurringTask;
+import com.github.kagkarlsson.scheduler.task.helper.Tasks;
+import com.github.kagkarlsson.scheduler.task.schedule.Daily;
+import java.time.LocalTime;
+import org.junit.jupiter.api.Test;
+
+class AbstractTaskTest {
+
+  @Test
+  void test_default_priority_with_data() {
+    RecurringTask<String> task =
+        Tasks.recurring("task", new Daily(LocalTime.MIDNIGHT), String.class)
+            .executeStateful((taskInstance, executionContext) -> "");
+
+    assertEquals(task.getDefaultPriority(), task.instance("id", "data").getPriority());
+  }
+
+  @Test
+  void test_default_priority_without_data() {
+    RecurringTask<Void> task =
+        Tasks.recurring("task", new Daily(LocalTime.MIDNIGHT))
+            .execute((taskInstance, executionContext) -> {});
+
+    assertEquals(task.getDefaultPriority(), task.instance("id").getPriority());
+  }
+}