This is a fork of Starkgate to enable the transfer of ZEND. Originally, the code written for Stargate only supports the legacy bridge. This fork modifies a little bit of code to support StarkTokenBridge, which is a generic bridge that can support multiple tokens in contrast to the legacy bridge that can only support a token per bridge.
Both L1→L2 and L2->L1 transfers of ZEND token are supported.
This bridge is meant to be a temporary measure until https://starkgate.starknet.io/ officially supports ZEND token. The code qualitiy is not maintained at its best and things might break.
Currently, Goerli is almost near the end of its life, and most RPC nodes and explorers are not really keen on maintaining the sync with it. However, very unfortunately Starkgate hasn't deployed StarknetTokenBridge on Sepolia, so Goerli needs to be used.
You can check the list of addresses at https://github.com/starknet-io/starknet-addresses/blob/master/bridged_tokens/sepolia.json and wait for MultiBridge to be added to sepolia.json.
To faciliate testing, an ERC20 MockZend contract was deployed to 0x7b1bf875977e4124dc781153bd6393c8e1c22739 on Goerli and enrollTokenBridge was called to add the token to StarknetTokenBridge. You can verify that MockZend has been added by calling get_l2_token(0x7b1bF875977E4124dc781153BD6393c8e1C22739) at https://testnet.starkscan.co/contract/0x0627582c893c1506750d28a40a2e781031554c16544ff7b390c117978bc03de7#read-write-contract, which should return 0x501ac4f2b0e06a088fc71e009ae54bc3c89ffca7b24b7e27a7966449d88ed6b which is the L2 token address for MockZend.
However, even the sync between Goerli Starknet and Goerli Ethereum is extremely slow, and the bridge transaction will at least take several hours to see the result on the other side.
Therefore, zkLend team has decided to test directly on mainnet, which turns out to be the easiest way. Testing on Goerli is not recommended. But if you need testing on Goerli, you can mint MockZend freely at https://goerli.etherscan.io/address/0x7b1bf875977e4124dc781153bd6393c8e1c22739#writeContract by calling freeMint or freeMintWithAmount. Optimistically, we will just wait for Starknet team to deploy the bridge contract on Sepolia.