I am trying to send a market.plutus file to test a NFT marketplace to mainnet. I am building the transaction here like this:

cardano-cli transaction build --alonzo-era --mainnet --tx-in $UTxO-VARIABLE --tx-out $CONTRACT-ADDR-VARIABLE+5400011 --tx-out-datum-hash 67882f9c671cb45fc6990a2d14a20b30bfce29ad99a401c283a100662e6600fb --metadata-json-file --change-address $MY-ADDR-VARIABLE --out-file tx.build

Notice how the --metadata-json-file field is empty. It doesn't let me build it empty of course but I have no idea what goes here or what it should be.