Refactor to junit5

- remove junit4 dependecies
- refactor the unit tests by junit5
- enhance the spring-statemachine-test and spring-statemachine-build-tests so they can work together with junit4/junit5
- relates #779

spring-statemachine-samples/tasks/src/test/java/demo/tasks/TasksTests.java

@@ -15,9 +15,9 @@
  */
 package demo.tasks;
 
+import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.contains;
 import static org.hamcrest.Matchers.is;
-import static org.junit.Assert.assertThat;
 import static org.springframework.statemachine.TestUtils.doStartAndAssert;
 import static org.springframework.statemachine.TestUtils.doStopAndAssert;
 
@@ -29,9 +29,9 @@ import java.util.concurrent.TimeUnit;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-import org.junit.After;
-import org.junit.Before;
-import org.junit.Test;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
@@ -138,7 +138,7 @@ public class TasksTests {
 	}
 
 	@SuppressWarnings("unchecked")
-	@Before
+	@BeforeEach
 	public void setup() throws Exception {
 		context = new AnnotationConfigApplicationContext();
 		context.register(CommonConfiguration.class, Application.class, TestConfig.class);
@@ -152,7 +152,7 @@ public class TasksTests {
 		assertThat(machine.getState().getIds(), contains(States.READY));
 	}
 
-	@After
+	@AfterEach
 	public void clean() {
 		doStopAndAssert(machine);
 		context.close();