Update PR based on review: Use enum instead of plain string

src/main/java/io/vertx/core/http/Cookie.java

@@ -121,12 +121,11 @@ public interface Cookie {
   /**
    * Sets the same site of this cookie.
    *
-   * @param policy The policy should be one of {@code Lax}, {@code Strict} or {@code None}
+   * @param policy The policy should be one of {@link CookieSameSite}.
    * @return a reference to this, so the API can be used fluently
    */
   @Fluent
-  Cookie setSameSite(String policy);
-
+  Cookie setSameSite(CookieSameSite policy);
 
   /**
    * Encode the cookie to a string. This is what is used in the Set-Cookie header

src/main/java/io/vertx/core/http/CookieSameSite.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2011-2019 Contributors to the Eclipse Foundation
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
+ * which is available at https://www.apache.org/licenses/LICENSE-2.0.
+ *
+ * SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
+ */
+package io.vertx.core.http;
+
+import io.vertx.codegen.annotations.VertxGen;
+
+/**
+ * Represents the Cookie SameSite policy to be used. For more info <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Cookies#SameSite_cookies">https://developer.mozilla.org/en-US/docs/Web/HTTP/Cookies#SameSite_cookies</a>.
+ *
+ * @author <a href="mailto:plopes@redhat.com">Paulo Lopes</a>
+ */
+@VertxGen
+public enum CookieSameSite {
+
+  /**
+   * The browser will send cookies with both cross-site requests and same-site requests.
+   */
+  NONE("None"),
+
+  /**
+   * The browser will only send cookies for same-site requests (requests originating from the site that set the cookie).
+   * If the request originated from a different URL than the URL of the current location, none of the cookies tagged
+   * with the Strict attribute will be included.
+   */
+  STRICT("Strict"),
+
+  /**
+   * Same-site cookies are withheld on cross-site subrequests, such as calls to load images or frames, but will be sent
+   * when a user navigates to the URL from an external site; for example, by following a link.
+   */
+  LAX("Lax");
+
+  /**
+   * Just use a human friendly label instead of the capitalized name.
+   */
+  private final String label;
+
+  CookieSameSite(String label) {
+    this.label = label;
+  }
+
+  @Override
+  public String toString() {
+    return label;
+  }
+}

src/main/java/io/vertx/core/http/impl/CookieImpl.java

@@ -15,6 +15,7 @@ import io.netty.handler.codec.http.cookie.DefaultCookie;
 import io.netty.handler.codec.http.cookie.ServerCookieDecoder;
 import io.netty.handler.codec.http.cookie.ServerCookieEncoder;
 import io.vertx.core.http.Cookie;
+import io.vertx.core.http.CookieSameSite;
 
 import java.util.HashMap;
 import java.util.Map;
@@ -64,7 +65,7 @@ public class CookieImpl implements ServerCookie {
   private boolean changed;
   private boolean fromUserAgent;
   // extension features
-  private String sameSite;
+  private CookieSameSite sameSite;
 
   public CookieImpl(String name, String value) {
     this.nettyCookie = new DefaultCookie(name, value);
@@ -139,30 +140,7 @@ public class CookieImpl implements ServerCookie {
   }
 
   @Override
-  public Cookie setSameSite(final String sameSite) {
-    if (sameSite != null) {
-      // validate
-      int length = sameSite.length();
-      switch (length) {
-        case 3:
-          if (!sameSite.equalsIgnoreCase("LAX")) {
-            throw new IllegalArgumentException("sameSite contains an invalid value: " + sameSite);
-          }
-          break;
-        case 4:
-          if (!sameSite.equalsIgnoreCase("NONE")) {
-            throw new IllegalArgumentException("sameSite contains an invalid value: " + sameSite);
-          }
-          break;
-        case 6:
-          if (!sameSite.equalsIgnoreCase("STRICT")) {
-            throw new IllegalArgumentException("sameSite contains an invalid value: " + sameSite);
-          }
-          break;
-        default:
-          throw new IllegalArgumentException("sameSite contains an invalid value: " + sameSite);
-      }
-    }
+  public Cookie setSameSite(final CookieSameSite sameSite) {
     this.sameSite = sameSite;
     this.changed = true;
     return this;
@@ -171,7 +149,7 @@ public class CookieImpl implements ServerCookie {
   @Override
   public String encode() {
     if (sameSite != null) {
-      return ServerCookieEncoder.STRICT.encode(nettyCookie) + "; SameSite=" + sameSite;
+      return ServerCookieEncoder.STRICT.encode(nettyCookie) + "; SameSite=" + sameSite.toString();
     } else {
       return ServerCookieEncoder.STRICT.encode(nettyCookie);
     }

src/test/java/io/vertx/core/http/HttpTest.java

@@ -5405,15 +5405,15 @@ public abstract class HttpTest extends HttpTestBase {
 
   @Test
   public void testCookieSameSiteFieldEncoding() throws Exception {
-    Cookie cookie = Cookie.cookie("foo", "bar").setSameSite("lax");
+    Cookie cookie = Cookie.cookie("foo", "bar").setSameSite(CookieSameSite.LAX);
     assertEquals("foo", cookie.getName());
     assertEquals("bar", cookie.getValue());
-    assertEquals("foo=bar; SameSite=lax", cookie.encode());
+    assertEquals("foo=bar; SameSite=Lax", cookie.encode());
 
     cookie.setSecure(true);
-    assertEquals("foo=bar; Secure; SameSite=lax", cookie.encode());
+    assertEquals("foo=bar; Secure; SameSite=Lax", cookie.encode());
     cookie.setHttpOnly(true);
-    assertEquals("foo=bar; Secure; HTTPOnly; SameSite=lax", cookie.encode());
+    assertEquals("foo=bar; Secure; HTTPOnly; SameSite=Lax", cookie.encode());
   }
 
   @Test
@@ -5421,36 +5421,17 @@ public abstract class HttpTest extends HttpTestBase {
     Cookie cookie = Cookie.cookie("foo", "bar");
 
     try {
-      cookie.setSameSite("Lax");
+      cookie.setSameSite(CookieSameSite.LAX);
       // OK
-      cookie.setSameSite("Strict");
+      cookie.setSameSite(CookieSameSite.STRICT);
       // OK
-      cookie.setSameSite("NoNe");
+      cookie.setSameSite(CookieSameSite.NONE);
       // OK
       cookie.setSameSite(null);
       // OK
     } catch (RuntimeException e) {
       fail();
     }
-
-    try {
-      cookie.setSameSite("XYZ");
-      fail();
-    } catch (RuntimeException e) {
-      // OK
-    }
-    try {
-      cookie.setSameSite("DURP");
-      fail();
-    } catch (RuntimeException e) {
-      // OK
-    }
-    try {
-      cookie.setSameSite("some random stuff");
-      fail();
-    } catch (RuntimeException e) {
-      // OK
-    }
   }
 
   @Test