Upgrade to Jetty 9.4.18.v20190429

Closes gh-16771

spring-boot-project/spring-boot-dependencies/pom.xml

@@ -104,7 +104,7 @@
 		<jedis.version>2.9.3</jedis.version>
 		<jersey.version>2.27</jersey.version>
 		<jest.version>6.3.1</jest.version>
-		<jetty.version>9.4.15.v20190215</jetty.version>
+		<jetty.version>9.4.18.v20190429</jetty.version>
 		<jetty-jsp.version>2.2.0.v201112011158</jetty-jsp.version>
 		<jetty-el.version>8.5.35.1</jetty-el.version>
 		<jetty-reactive-httpclient.version>1.0.3</jetty-reactive-httpclient.version>