Fix checkstyle errors

spring-webflux/src/test/java/org/springframework/web/reactive/result/view/AbstractViewTests.java

@@ -37,7 +37,9 @@ import org.springframework.validation.BindingResult;
 import org.springframework.web.reactive.BindingContext;
 import org.springframework.web.server.ServerWebExchange;
 
-import static org.junit.Assert.*;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
 
 /**
  * Unit tests for {@link AbstractView}.