Is the format of this file https://github.com/ElrondNetwork/sc-nft-collection-minter/blob/main/nft-minter/src/nft_attributes_builder.rs#L117 documented anywhere>?

hey Catalin ! the format is not yet documented since we are still reviewing everything internally. But yes, it's the output of what we want to finally merge in hashlips - we started from eth-style output and changed it a bit to our needs and also be as compatible as possible with existing markets on Elrond. You can test and generate example (or real) outputs from the code in this PR: https://github.com/ElrondNetwork/hashlips_art_engine/pull/1

cc @ccorcoveanu ?

maybe @LucianMincu? sorry for ping but i dont know who to ask. the author (dorin) doesnt know either

IMO the collection.json is probably an additional metadata file with information about the whole collection, stored under the IPFS CID ('collection_hash' here). It will likely hold a rarity and other collection info. I think Trust Market also uses it, so maybe the official marketplace will also use it. I think it isn't a standard or at least not yet. Perhaps it will be the Elrond NFT metadata standard? I don't think that hashlips generates such file, but maybe they've changed something lately.