MessageReactionAddData
constructor(userId: Snowflake, channelId: Snowflake, messageId: Snowflake, guildId: OptionalSnowflake = OptionalSnowflake.Missing, member: Optional<DiscordGuildMember> = Optional.Missing(), emoji: DiscordPartialEmoji, messageAuthorId: OptionalSnowflake = OptionalSnowflake.Missing)(source)