Function resolve_transaction 

pub fn resolve_transaction<DB, Tx, T>(
    tx: <<T as RpcConvert>::Network as RpcTypes>::TransactionRequest,
    default_gas_limit: u64,
    block_base_fee_per_gas: u64,
    chain_id: u64,
    db: &mut DB,
    tx_resp_builder: &T,
) -> Result<Recovered<Tx>, EthApiError>
where
    DB: Database,
    <DB as Database>::Error: Into<EthApiError>,
    T: RpcConvert,
    <T as RpcConvert>::Primitives: NodePrimitives<SignedTx = Tx>,

Available on crate feature rpc only.

Goes over the list of TransactionRequests and populates missing fields trying to resolve them into primitive transactions.

This will set the defaults as defined in https://github.com/ethereum/execution-apis/blob/e56d3208789259d0b09fa68e9d8594aa4d73c725/docs/ethsimulatev1-notes.md#default-values-for-transactions