Make Tomcat javadoc link version dependent

See gh-19632

spring-boot-project/spring-boot-docs/build.gradle

@@ -58,12 +58,14 @@ task javadoc(type: Javadoc) {
 		}
 		doFirst {
 			def versionConstraints = dependencyVersions.versionConstraints
+			def tomcatVersion = "${versionConstraints['org.apache.tomcat:tomcat-annotations-api']}"
+			def tomcatDocsVersion = tomcatVersion.substring(0, tomcatVersion.lastIndexOf('.'));
 			options.links = [
 				'https://docs.oracle.com/javase/8/docs/api/',
 				'https://docs.oracle.com/javaee/7/api/',
 				"https://docs.spring.io/spring-framework/docs/${versionConstraints['org.springframework:spring-core']}/javadoc-api/",
 				"https://docs.spring.io/spring-security/site/docs/${versionConstraints['org.springframework.security:spring-security-core']}/api/",
-				'https://tomcat.apache.org/tomcat-9.0-doc/api/',
+				"https://tomcat.apache.org/tomcat-${tomcatDocsVersion}-doc/api/",
 				"https://www.eclipse.org/jetty/javadoc/${versionConstraints['org.eclipse.jetty:jetty-server']}/",
 				"https://www.thymeleaf.org/apidocs/thymeleaf/${versionConstraints['org.thymeleaf:thymeleaf']}/"
 			] as String[]