Upgrade to Jetty 9.4.8.v20171121

Closes gh-11469

spring-boot-dependencies/pom.xml

@@ -111,7 +111,7 @@
 		<jedis.version>2.9.0</jedis.version>
 		<jersey.version>2.25.1</jersey.version>
 		<jest.version>2.0.4</jest.version>
-		<jetty.version>9.4.7.v20170914</jetty.version>
+		<jetty.version>9.4.8.v20171121</jetty.version>
 		<jetty-jsp.version>2.2.0.v201112011158</jetty-jsp.version>
 		<jetty-el.version>8.0.33</jetty-el.version>
 		<jms-api.version>1.1-rev-1</jms-api.version>

spring-boot-starters/spring-boot-starter-jetty/pom.xml

@@ -63,6 +63,9 @@
 							<goal>check</goal>
 						</goals>
 						<configuration>
+							<ignoredClassPatterns>
+								<ignoredClassPattern>^module-info$</ignoredClassPattern>
+							</ignoredClassPatterns>
 							<ignoredResourcePatterns>
 								<ignoredResourcePattern>about.html</ignoredResourcePattern>
 							</ignoredResourcePatterns>

spring-boot/src/test/java/org/springframework/boot/context/embedded/jetty/JettyEmbeddedServletContainerFactoryTests.java

@@ -382,6 +382,7 @@ public class JettyEmbeddedServletContainerFactoryTests
 			return null;
 		}
 		holder.start();
+		holder.initialize();
 		return (JspServlet) holder.getServlet();
 	}