Add blank line between java and javax imports

See gh-23539

Co-authored-by: Sam Brannen <sbrannen@pivotal.io>

spring-aop/src/test/java/org/springframework/aop/framework/ProxyFactoryTests.java

@@ -18,6 +18,7 @@ package org.springframework.aop.framework;
 
 import java.util.ArrayList;
 import java.util.List;
+
 import javax.accessibility.Accessible;
 import javax.swing.JFrame;
 import javax.swing.RootPaneContainer;