Add dependency now needed for javadoc generation on Java 11

See gh-15775

Author: wilkinsona

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

@@ -562,6 +562,11 @@
 			<artifactId>jersey-container-servlet-core</artifactId>
 			<optional>true</optional>
 		</dependency>
+		<dependency>
+			<groupId>org.glassfish.jersey.ext</groupId>
+			<artifactId>jersey-spring4</artifactId>
+			<optional>true</optional>
+		</dependency>
 		<dependency>
 			<groupId>org.glassfish.jersey.media</groupId>
 			<artifactId>jersey-media-json-jackson</artifactId>