fix resttemplate CustomTest for JUnit 5

Author: martin-mfg

samples/client/echo_api/java/resttemplate/src/test/java/org/openapitools/client/CustomTest.java

@@ -13,22 +13,20 @@
 
 package org.openapitools.client;
 
-import org.junit.Assert;
-import org.junit.Test;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
 import org.openapitools.client.api.BodyApi;
 import org.openapitools.client.api.QueryApi;
 import org.openapitools.client.model.Category;
 import org.openapitools.client.model.Pet;
 
 import java.util.Arrays;
 
-import static org.junit.Assert.assertNotNull;
-
 
 /**
  * API tests
  */
-public class CustomTest {
+class CustomTest {
 
     private final QueryApi api = new QueryApi();
     private final BodyApi bodyApi = new BodyApi();
@@ -40,22 +38,22 @@ public class CustomTest {
      *
      */
     @Test
-    public void testEchoBodyPet() {
+    void testEchoBodyPet() {
         Pet pet = new Pet().id(12345L).name("Hello World").
                 photoUrls(Arrays.asList(new String[]{"http://a.com", "http://b.com"})).category(new Category().id(987L).name("new category"));
 
         Pet p = bodyApi.testEchoBodyPet(pet);
-        assertNotNull(p);
-        Assert.assertEquals("Hello World", p.getName());
-        Assert.assertEquals(Long.valueOf(12345L), p.getId());
+        Assertions.assertNotNull(p);
+        Assertions.assertEquals("Hello World", p.getName());
+        Assertions.assertEquals(Long.valueOf(12345L), p.getId());
 
         // response is empty body
         Pet p2 = bodyApi.testEchoBodyPet(null);
-        Assert.assertNull(p2);
+        Assertions.assertNull(p2);
     }
 
     @Test
-    public void testQueryParamsExploded_whenQueryParamIsNull() {
-        assertNotNull(api.testQueryStyleFormExplodeTrueObject(null));
+    void testQueryParamsExploded_whenQueryParamIsNull() {
+        Assertions.assertNotNull(api.testQueryStyleFormExplodeTrueObject(null));
     }
 }