Polish AssertJ assertions

Fixes gh-4770

samples/javaconfig/data/src/test/java/samples/data/SecurityMessageRepositoryTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -63,7 +63,7 @@ public class SecurityMessageRepositoryTests {
 	public void findAllOnlyToCurrentUser() {
 		Long expectedId = user.getId();
 		List<Message> messages = repository.findAll();
-		assertThat(messages.size()).isEqualTo(3);
+		assertThat(messages).hasSize(3);
 		for (Message m : messages) {
 			assertThat(m.getTo().getId()).isEqualTo(expectedId);
 		}