Merge pull request #20390 from gir1yaphets

* pr/20390:
  Polish "Refine if statement logic"
  Refine if statement logic

Closes gh-20390

spring-boot-project/spring-boot-cli/src/main/java/org/springframework/boot/cli/compiler/grape/DefaultRepositorySystemSessionAutoConfiguration.java

 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -48,7 +48,7 @@ public class DefaultRepositorySystemSessionAutoConfiguration implements Reposito
 		}
 
 		ProxySelector existing = session.getProxySelector();
-		if (existing == null || !(existing instanceof CompositeProxySelector)) {
+		if (!(existing instanceof CompositeProxySelector)) {
 			JreProxySelector fallback = new JreProxySelector();
 			ProxySelector selector = (existing != null) ? new CompositeProxySelector(Arrays.asList(existing, fallback))
 					: fallback;