{
// Required fields
chat_group_id: Id;
content: Html;
}Creates a new chat_message for the chat_group given by the key chat_group_id. The requesting user's id is registered by the key user_id in the new chat_message-object and a creation timestamp is set (see field created).
Every user, who is in one of the write groups of a chat group, or has the permission chat.can_manage can create a chat_message.
User also needs to be part of the meeting.