Add support for webhook types

src/main/java/net/dv8tion/jda/api/entities/Webhook.java

@@ -43,6 +43,15 @@ public interface Webhook extends ISnowflake, IFakeable
     @Nonnull
     JDA getJDA();
 
+    /**
+     * The {@link WebhookType} of this webhook.
+     * <br>Webhooks of type {@link WebhookType#FOLLOWER} don't have a token.
+     *
+     * @return The {@link WebhookType}
+     */
+    @Nonnull
+    WebhookType getType();
+
     /**
      * The {@link net.dv8tion.jda.api.entities.Guild Guild} instance
      * for this Webhook.

src/main/java/net/dv8tion/jda/api/entities/WebhookType.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2015-2019 Austin Keener, Michael Ritter, Florian Spieß, and the JDA contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.dv8tion.jda.api.entities;
+
+import javax.annotation.Nonnull;
+
+public enum WebhookType
+{
+    /** Placeholder for unsupported types */
+    UNKNOWN(-1),
+    /** Normal webhooks that can be used for sending messages */
+    INCOMING(1),
+    /** Webhook responsible for re-posting messages from another channel */
+    FOLLOWER(2);
+
+    private final int key;
+
+    WebhookType(int key)
+    {
+        this.key = key;
+    }
+
+    /**
+     * The raw api key for this type
+     *
+     * @return The api key, or -1 for {@link #UNKNOWN}
+     */
+    public int getKey()
+    {
+        return key;
+    }
+
+    /**
+     * Resolves the provided raw api key to the corresponding webhook type.
+     *
+     * @param  key
+     *         The key
+     *
+     * @return The WebhookType or {@link #UNKNOWN}
+     */
+    @Nonnull
+    public static WebhookType fromKey(int key)
+    {
+        for (WebhookType type : values())
+        {
+            if (type.key == key)
+                return type;
+        }
+        return UNKNOWN;
+    }
+}

src/main/java/net/dv8tion/jda/internal/entities/EntityBuilder.java

@@ -1151,6 +1151,7 @@ public WebhookImpl createWebhook(DataObject object)
         final long guildId = object.getLong("guild_id");
         final long channelId = object.getLong("channel_id");
         final String token = object.getString("token", null);
+        final WebhookType type = WebhookType.fromKey(object.getInt("type", -1));
 
         TextChannel channel = getJDA().getTextChannelById(channelId);
         if (channel == null)
@@ -1183,7 +1184,7 @@ public WebhookImpl createWebhook(DataObject object)
             }
         }
 
-        return new WebhookImpl(channel, id)
+        return new WebhookImpl(channel, id, type)
                 .setToken(token)
                 .setOwner(owner == null ? null : channel.getGuild().getMember(owner))
                 .setUser(defaultUser);

src/main/java/net/dv8tion/jda/internal/entities/WebhookImpl.java

@@ -44,15 +44,24 @@ public class WebhookImpl implements Webhook
     private final ReentrantLock mngLock = new ReentrantLock();
     private final TextChannel channel;
     private final long id;
+    private final WebhookType type;
 
     private Member owner;
     private User user;
     private String token;
 
-    public WebhookImpl(TextChannel channel, long id)
+    public WebhookImpl(TextChannel channel, long id, WebhookType type)
     {
         this.channel = channel;
         this.id = id;
+        this.type = type;
+    }
+
+    @Nonnull
+    @Override
+    public WebhookType getType()
+    {
+        return type;
     }
 
     @Nonnull