Polish contribution

Closes gh-14592

Author: snicoll

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/context/SpringBootContextLoader.java

@@ -18,10 +18,7 @@
 
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.Collections;
-import java.util.LinkedHashSet;
 import java.util.List;
-import java.util.Set;
 
 import org.springframework.beans.BeanUtils;
 import org.springframework.boot.SpringApplication;