Recommend disabling context root redirects with proxied Tomcat

Closes gh-22908

Author: wilkinsona

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/ServerProperties.java

@@ -372,7 +372,8 @@ public static class Tomcat {
 
 		/**
 		 * Whether requests to the context root should be redirected by appending a / to
-		 * the path.
+		 * the path. When using SSL terminated at a proxy, this property should be set to
+		 * false.
 		 */
 		private Boolean redirectContextRoot = true;
 

spring-boot-project/spring-boot-docs/src/main/asciidoc/howto.adoc

@@ -856,6 +856,9 @@ With this option, the Web servers themselves natively support this feature; you
 If this is not enough, Spring Framework provides a {spring-framework-docs}web.html#filters-forwarded-headers[ForwardedHeaderFilter].
 You can register it as a Servlet Filter in your application by setting `server.forward-headers-strategy` is set to `FRAMEWORK`.
 
+TIP: If you are using Tomcat and terminating SSL at the proxy, configprop:server.tomcat.redirect-context-root[] should be set to `false`.
+This allows the `X-Forwarded-Proto` header to be honored before any redirects are performed.
+
 NOTE: If your application runs in Cloud Foundry or Heroku, the configprop:server.forward-headers-strategy[] property defaults to `NATIVE`.
 In all other instances, it defaults to `NONE`.