Remove public modifier on JUnit5 lifecycle methods

See gh-17292

spring-boot-samples/spring-boot-sample-data-rest/src/test/java/sample/data/rest/SampleDataRestApplicationTests.java

@@ -49,7 +49,7 @@ class SampleDataRestApplicationTests {
 	private MockMvc mvc;
 
 	@BeforeEach
-	public void setUp() {
+	void setUp() {
 		this.mvc = MockMvcBuilders.webAppContextSetup(this.context).build();
 	}