Add support for user-installable apps (#2633)

* Add contexts and integration types
* Update tests and examples
* Add ApplicationInfo fields
* Add Interaction fields (context, integration owners)
* Add Message fields (interaction metadata)
* Add IDetachableEntity
* Pull up IPermissionHolder#hasPermission overloads with Collection
* Add concrete entity mixins
* Add Interaction#isFromAttachedGuild
* Add InteractionEntityBuilder, adapt entity deserialization
* Add group channel support
* Add ErrorResponse#MAX_FOLLOW_UP_MESSAGES_HIT
* Add user-installed slash command example
* Add approximate user install count
* Add Helpers#unmodifiableEnumSet
* Add IntegrationOwners#isXIntegration()/getXIntegration()
* Reword #setEphemeral note

Author: freya022

src/examples/java/SlashBotExample.java

@@ -23,6 +23,8 @@
 import net.dv8tion.jda.api.events.interaction.command.SlashCommandInteractionEvent;
 import net.dv8tion.jda.api.events.interaction.component.ButtonInteractionEvent;
 import net.dv8tion.jda.api.hooks.ListenerAdapter;
+import net.dv8tion.jda.api.interactions.IntegrationType;
+import net.dv8tion.jda.api.interactions.InteractionContextType;
 import net.dv8tion.jda.api.interactions.InteractionHook;
 import net.dv8tion.jda.api.interactions.commands.DefaultMemberPermissions;
 import net.dv8tion.jda.api.interactions.commands.OptionMapping;
@@ -45,7 +47,7 @@ public static void main(String[] args)
                 .addEventListeners(new SlashBotExample())
                 .build();
 
-        // These commands might take a few minutes to be active after creation/update/delete
+        // You might need to reload your Discord client if you don't see the commands
         CommandListUpdateAction commands = jda.updateCommands();
 
         // Moderation commands with required options
@@ -56,27 +58,33 @@ public static void main(String[] args)
                 .addOptions(new OptionData(INTEGER, "del_days", "Delete messages from the past days.") // This is optional
                     .setRequiredRange(0, 7)) // Only allow values between 0 and 7 (inclusive)
                 .addOptions(new OptionData(STRING, "reason", "The ban reason to use (default: Banned by <user>)")) // optional reason
-                .setGuildOnly(true) // This way the command can only be executed from a guild, and not the DMs
+                .setContexts(InteractionContextType.GUILD) // This way the command can only be executed from a guild, and not the DMs
                 .setDefaultPermissions(DefaultMemberPermissions.enabledFor(Permission.BAN_MEMBERS)) // Only members with the BAN_MEMBERS permission are going to see this command
         );
 
         // Simple reply commands
         commands.addCommands(
             Commands.slash("say", "Makes the bot say what you tell it to")
+                .setContexts(InteractionContextType.ALL) // Allow the command to be used anywhere (Bot DMs, Guild, Friend DMs, Group DMs)
+                .setIntegrationTypes(IntegrationType.ALL) // Allow the command to be installed anywhere (Guilds, Users)
                 .addOption(STRING, "content", "What the bot should say", true) // you can add required options like this too
         );
 
         // Commands without any inputs
         commands.addCommands(
             Commands.slash("leave", "Make the bot leave the server")
-                .setGuildOnly(true) // this doesn't make sense in DMs
+                // The default integration types are GUILD_INSTALL.
+                // Can't use this in DMs, and in guilds the bot isn't in.
+                .setContexts(InteractionContextType.GUILD)
                 .setDefaultPermissions(DefaultMemberPermissions.DISABLED) // only admins should be able to use this command.
         );
 
         commands.addCommands(
             Commands.slash("prune", "Prune messages from this channel")
                 .addOption(INTEGER, "amount", "How many messages to prune (Default 100)") // simple optional argument
-                .setGuildOnly(true)
+                // The default integration types are GUILD_INSTALL.
+                // Can't use this in DMs, and in guilds the bot isn't in.
+                .setContexts(InteractionContextType.GUILD)
                 .setDefaultPermissions(DefaultMemberPermissions.enabledFor(Permission.MESSAGE_MANAGE))
         );
 

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

@@ -18,16 +18,14 @@
 
 import net.dv8tion.jda.api.JDA;
 import net.dv8tion.jda.api.Permission;
+import net.dv8tion.jda.api.interactions.IntegrationType;
 import net.dv8tion.jda.api.utils.ImageProxy;
 import net.dv8tion.jda.internal.utils.Checks;
 import org.jetbrains.annotations.Unmodifiable;
 
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.EnumSet;
-import java.util.List;
+import java.util.*;
 
 /**
  * Represents a Discord Application from its bot's point of view.
@@ -116,7 +114,7 @@ default ImageProxy getIcon()
 
     /**
      * Configures the required scopes applied to the {@link #getInviteUrl(Permission...)} and similar methods.
-     * <br>To use slash commands you must add {@code "applications.commands"} to these scopes. The scope {@code "bot"} is always applied.
+     * <br>The scope {@code "bot"} is always applied.
      *
      * @param  scopes
      *         The scopes to use with {@link #getInviteUrl(Permission...)} and the likes
@@ -135,7 +133,7 @@ default ApplicationInfo setRequiredScopes(@Nonnull String... scopes)
 
     /**
      * Configures the required scopes applied to the {@link #getInviteUrl(Permission...)} and similar methods.
-     * <br>To use slash commands you must add {@code "applications.commands"} to these scopes. The scope {@code "bot"} is always applied.
+     * <br>The scope {@code "bot"} is always applied.
      *
      * @param  scopes
      *         The scopes to use with {@link #getInviteUrl(Permission...)} and the likes
@@ -408,6 +406,64 @@ default EnumSet<Flag> getFlags()
      */
     long getFlagsRaw();
 
+    /**
+     * The approximate count of users that have installed this application,
+     * or {@code -1} if it is unknown.
+     *
+     * @return The approximate count of users that have installed this application.
+     */
+    long getUserInstallCount();
+
+    /**
+     * The configurations for each {@link IntegrationType} set on the application.
+     *
+     * @return The configurations for each integration type
+     */
+    @Nonnull
+    Map<IntegrationType, IntegrationTypeConfiguration> getIntegrationTypesConfig();
+
+    /**
+     * Configuration of a single {@link IntegrationType}.
+     *
+     * @see ApplicationInfo#getIntegrationTypesConfig()
+     */
+    interface IntegrationTypeConfiguration
+    {
+        /**
+         * The OAuth2 install parameters for the default in-app authorization link.
+         * <br>When a user invites your application in the Discord app, these will be the parameters of the invite url.
+         *
+         * @return The OAuth2 install parameters for the default in-app authorization link
+         */
+        @Nullable
+        InstallParameters getInstallParameters();
+    }
+
+    /**
+     * OAuth2 install parameter for the default in-app authorization link.
+     *
+     * @see IntegrationTypeConfiguration#getInstallParameters()
+     */
+    interface InstallParameters
+    {
+        /**
+         * Gets the required scopes granted to the bot when invited.
+         *
+         * @return The required scopes granted to the bot when invited
+         */
+        @Nonnull
+        List<String> getScopes();
+
+        /**
+         * Gets the permissions your bot asks for when invited.
+         * <br><b>Note:</b> Users can choose to disable permissions before and after inviting your bot.
+         *
+         * @return The permissions your bot asks for when invited
+         */
+        @Nonnull
+        Set<Permission> getPermissions();
+    }
+
     /**
      * Flag constants corresponding to the <a href="https://discord.com/developers/docs/resources/application#application-object-application-flags" target="_blank">Discord Enum</a>
      *