FetchAssetMeta currently requires one of the following

as in input.

We should also accept group_key as there can be many asset_id in a group. Different each asset_id in a group can have different metadata, so we should return an array of metadata for all asset_id in the group_key.

However, there is a special case of data that is normally embedded in the metadata, the decimal_display. This is not supposed to change, so we should decode and return that value in a separate property. See also, #1503 . Alternatively, if we don't want to include the group's decimal_display value in the response to FetchAssetMeta, we should create a new RPC that does.