getPaymentInstruction

const paymentInfo = await client.getPaymentInstruction({
  transaction: "base64EncodedTransaction",
  fee_token: "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
  source_wallet: "sourceWalletPublicKey"
});
// Append paymentInfo.payment_instruction to your transaction

{
  "original_transaction": "base64EncodedTransaction",
  "payment_address": "3Z1Ef7YaxK8oUMoi6exf7wYZjZKWJJsrzJXSt1c3qrDE",
  "payment_amount": 0,
  "payment_instruction": {},
  "payment_token": "exampleValue",
  "signer_address": "3Z1Ef7YaxK8oUMoi6exf7wYZjZKWJJsrzJXSt1c3qrDE"
}