Add filter Kotlin samples to docs

Issue gh-8172

docs/manual/src/docs/asciidoc/_includes/servlet/architecture/filters.adoc

@@ -21,7 +21,8 @@ The power of the `Filter` comes from the `FilterChain` that is passed into it.
 
 .`FilterChain` Usage Example
 ====
-[source,java]
+.Java
+[source,java,role="primary"]
 ----
 public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) {
 	// do something before the rest of the application
@@ -29,6 +30,16 @@ public void doFilter(ServletRequest request, ServletResponse response, FilterCha
     // do something after the rest of the application
 }
 ----
+
+.Kotlin
+[source,kotlin,role="secondary"]
+----
+fun doFilter(request: ServletRequest, response: ServletResponse, chain: FilterChain) {
+    // do something before the rest of the application
+    chain.doFilter(request, response) // invoke the rest of the application
+    // do something after the rest of the application
+}
+----
 ====
 
 Since a `Filter` only impacts downstream ``Filter``s and the `Servlet`, the order each `Filter` is invoked is extremely important.