Add support for gif stickers (#2377)

Author: MinnDevelopment

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

@@ -4582,7 +4582,7 @@ default RoleAction createCopyOfRole(@Nonnull Role role)
      * @param  description
      *         The sticker description (2-100 characters, or empty)
      * @param  file
-     *         The sticker file containing the asset (png/apng/lottie) with valid file extension (png or json)
+     *         The sticker file containing the asset (png/apng/gif/lottie) with valid file extension (png, gif, or json)
      * @param  tags
      *         The tags to use for auto-suggestions (Up to 200 characters in total)
      *
@@ -4592,7 +4592,7 @@ default RoleAction createCopyOfRole(@Nonnull Role role)
      *         <ul>
      *             <li>If the name is not between 2 and 30 characters long</li>
      *             <li>If the description is more than 100 characters long or exactly 1 character long</li>
-     *             <li>If the asset file is null or of an invalid format (must be PNG or LOTTIE)</li>
+     *             <li>If the asset file is null or of an invalid format (must be PNG, GIF, or LOTTIE)</li>
      *             <li>If anything is {@code null}</li>
      *         </ul>
      *
@@ -4618,7 +4618,7 @@ default RoleAction createCopyOfRole(@Nonnull Role role)
      * @param  description
      *         The sticker description (2-100 characters, or empty)
      * @param  file
-     *         The sticker file containing the asset (png/apng/lottie) with valid file extension (png or json)
+     *         The sticker file containing the asset (png/apng/gif/lottie) with valid file extension (png, gif, or json)
      * @param  tag
      *         The sticker tag used for suggestions (emoji or tag words)
      * @param  tags
@@ -4630,7 +4630,7 @@ default RoleAction createCopyOfRole(@Nonnull Role role)
      *         <ul>
      *             <li>If the name is not between 2 and 30 characters long</li>
      *             <li>If the description is more than 100 characters long or exactly 1 character long</li>
-     *             <li>If the asset file is null or of an invalid format (must be PNG or LOTTIE)</li>
+     *             <li>If the asset file is null or of an invalid format (must be PNG, GIF, or LOTTIE)</li>
      *             <li>If anything is {@code null}</li>
      *         </ul>
      *

src/main/java/net/dv8tion/jda/api/entities/sticker/Sticker.java

@@ -145,6 +145,10 @@ enum StickerFormat
          * @see <a href="https://airbnb.io/lottie/">Lottie website</a>
          */
         LOTTIE(3, "json"),
+        /**
+         * The GIF format.
+         */
+        GIF(4, "gif"),
         /**
          * Represents any unknown or unsupported format types.
          */

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

@@ -1785,7 +1785,7 @@ public AuditableRestAction<GuildSticker> createSticker(@Nonnull String name, @No
 
         // Extract file extension and map to media type
         int index = file.getName().lastIndexOf('.');
-        Checks.check(index > -1, "Filename for sticker is missing file extension. Provided: '" + file.getName() + "'. Must be PNG or JSON.");
+        Checks.check(index > -1, "Filename for sticker is missing file extension. Provided: '" + file.getName() + "'. Must be PNG, GIF, or JSON.");
 
         // Convert file extension to media-type
         String extension = file.getName().substring(index + 1).toLowerCase(Locale.ROOT);
@@ -1796,11 +1796,14 @@ public AuditableRestAction<GuildSticker> createSticker(@Nonnull String name, @No
             case "png":
                 mediaType = Requester.MEDIA_TYPE_PNG;
                 break;
+            case "gif":
+                mediaType = Requester.MEDIA_TYPE_GIF;
+                break;
             case "json":
                 mediaType = Requester.MEDIA_TYPE_JSON;
                 break;
             default:
-                throw new IllegalArgumentException("Unsupported file extension: '." + extension + "', must be PNG or JSON.");
+                throw new IllegalArgumentException("Unsupported file extension: '." + extension + "', must be PNG, GIF, or JSON.");
         }
 
         // Add sticker metadata as form parts (because payload_json is broken)

src/main/java/net/dv8tion/jda/internal/requests/Requester.java

@@ -55,6 +55,7 @@ public class Requester
     public static final MediaType MEDIA_TYPE_JSON  = MediaType.parse("application/json; charset=utf-8");
     public static final MediaType MEDIA_TYPE_OCTET = MediaType.parse("application/octet-stream; charset=utf-8");
     public static final MediaType MEDIA_TYPE_PNG = MediaType.parse("image/png");
+    public static final MediaType MEDIA_TYPE_GIF = MediaType.parse("image/gif");
 
     protected final JDAImpl api;
     protected final AuthorizationConfig authConfig;