One-time initializer. Stores gateway, expected source chain, and source address. source_address should be the StellarGateway.sol address e.g. "0x2BC0..."
fn init(
env: soroban_sdk::Env,
gateway: soroban_sdk::Address,
source_chain: soroban_sdk::String,
source_address: soroban_sdk::String,
)fn execute(
env: soroban_sdk::Env,
source_chain: soroban_sdk::String,
message_id: soroban_sdk::String,
source_address: soroban_sdk::String,
payload: soroban_sdk::Bytes,
) -> Result<(), __VaultAxelarExecutableInterfaceError>fn gateway(env: soroban_sdk::Env) -> soroban_sdk::Address