[UNDERTOW-2523] Add support for HttpSession.getAccessor().

Author: pferraro

core/src/main/java/io/undertow/server/session/Session.java

@@ -189,4 +189,12 @@ public interface Session {
      * @return <ul><li><b>true</b> - if session is no longer valid</li><li><b>false</b> - otherwise</li></ul>
      */
     boolean isInvalid();
+
+    /**
+     * Returns a detached view of this session for use outside of request scope.
+     * @return a detached view of this session for use outside of request scope.
+     */
+    default Session detach() {
+        return this;
+    }
 }

servlet/src/main/java/io/undertow/servlet/spec/HttpSessionImpl.java

@@ -23,10 +23,10 @@
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.Set;
+import java.util.function.Consumer;
 
 import jakarta.servlet.ServletContext;
 import jakarta.servlet.http.HttpSession;
-
 import io.undertow.server.session.Session;
 import io.undertow.servlet.UndertowServletMessages;
 import io.undertow.servlet.handlers.ServletRequestContext;
@@ -175,6 +175,18 @@ public boolean isNew() {
         return newSession;
     }
 
+    @Override
+    public Accessor getAccessor() {
+        Session detached = this.session.detach();
+        ServletContext context = this.servletContext;
+        return new Accessor() {
+            @Override
+            public void access(Consumer<HttpSession> consumer) {
+                consumer.accept(new HttpSessionImpl(detached, context, false, null));
+            }
+        };
+    }
+
     @SuppressWarnings("removal")
     public Session getSession() {
         SecurityManager sm = System.getSecurityManager();