Fix checkstyle issue

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/reactive/WebFluxProperties.java

@@ -44,7 +44,7 @@ public class WebFluxProperties {
 	private String staticPathPattern = "/**";
 
 	public String getBasePath() {
-		return basePath;
+		return this.basePath;
 	}
 
 	public void setBasePath(String basePath) {