Document redirect options in RESTEasy Reactive

Closes: quarkusio#28781

Co-authored-by: George Gastaldi <[email protected]>

docs/src/main/asciidoc/resteasy-reactive.adoc

@@ -780,6 +780,79 @@ public class Endpoint {
 }
 ----
 
+=== Redirect support
+
+When handling a `@POST`, `@PUT` or `@DELETE` endpoint, it is common practice to redirect to a `@GET` endpoint after the action has been performed to allow the user to reload the page without triggering the action a second time.
+There are multiple ways to achieve this.
+
+==== Using RestResponse
+
+Using `RestResponse` as the return type while making sure the proper redirection URI is created can be done as in the following example:
+
+[source,java]
+----
+package org.acme.rest;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicLong;
+import javax.ws.rs.GET;
+import javax.ws.rs.POST;
+import javax.ws.rs.Path;
+import javax.ws.rs.core.Context;
+import javax.ws.rs.core.UriInfo;
+import org.jboss.resteasy.reactive.RestResponse;
+
+@Path("/fruits")
+public class FruitResource {
+
+    public static class Fruit {
+        public Long id;
+        public String name;
+        public String description;
+
+        public Fruit() {
+        }
+
+        public Fruit(Long id, String name, String description) {
+            this.id = id;
+            this.name = name;
+            this.description = description;
+        }
+    }
+
+    private final Map<Long, Fruit> fruits = new ConcurrentHashMap<>();
+    private final AtomicLong ids = new AtomicLong(0);
+
+
+    public FruitResource() {
+        Fruit apple = new Fruit(ids.incrementAndGet(), "Apple", "Winter fruit");
+        fruits.put(apple.id, apple);
+        Fruit pinneapple = new Fruit(ids.incrementAndGet(), "Pineapple", "Tropical fruit");
+        fruits.put(pinneapple.id, pinneapple);
+    }
+
+    // when invoked, this method will result in an HTTP redirect to the GET method that obtains the fruit by id
+    @POST
+    public RestResponse<Fruit> add(Fruit fruit, @Context UriInfo uriInfo) {
+        fruit.id = ids.incrementAndGet();
+        fruits.put(fruit.id, fruit);
+        // seeOther results in an HTTP 303 response with the Location header set to the value of the URI
+        return RestResponse.seeOther(uriInfo.getAbsolutePathBuilder().path(Long.toString(fruit.id)).build());
+    }
+
+    @GET
+    @Path("{id}")
+    public Fruit byId(Long id) {
+        return fruits.get(id);
+    }
+}
+----
+
+==== Using RedirectException
+
+Users can also throw `javax.ws.rs.RedirectionException` from a method body to get RESTEasy Reactive to perform the desired redirect.
+
 === Async/reactive support
 
 [[reactive]]