test: migrate ElasticsearchStackoverflowTest to JUnit 5 (#4473)

src/test/java/spoon/test/reference/ElasticsearchStackoverflowTest.java

@@ -16,7 +16,10 @@
  */
 package spoon.test.reference;
 
-import org.junit.Test;
+
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
 import spoon.Launcher;
 import spoon.reflect.CtModel;
 import spoon.reflect.declaration.CtType;
@@ -26,12 +29,10 @@
 import spoon.reflect.visitor.CtScanner;
 import spoon.reflect.visitor.filter.TypeFilter;
 
-import java.util.List;
-
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 public class ElasticsearchStackoverflowTest {