Fix checkstyle errors

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/mvc/ShutdownMvcEndpoint.java

@@ -17,7 +17,6 @@
 package org.springframework.boot.actuate.endpoint.mvc;
 
 import java.util.Collections;
-import java.util.Map;
 
 import org.springframework.boot.actuate.endpoint.ShutdownEndpoint;
 import org.springframework.boot.context.properties.ConfigurationProperties;

spring-boot/src/test/java/org/springframework/boot/web/servlet/AbstractFilterRegistrationBeanTests.java

@@ -26,7 +26,6 @@ import java.util.Map;
 import javax.servlet.DispatcherType;
 import javax.servlet.Filter;
 import javax.servlet.FilterRegistration;
-import javax.servlet.Servlet;
 import javax.servlet.ServletContext;
 
 import org.junit.Before;