Payment Abstraction accomplishes the four-step conversion process through the introduction of multiple smart contracts, including: FeeAggregator.sol: A smart contract on the service chains where fee payments are collected and on the payment chain (Ethereum) where fees are accumulated after bridging. This contract is capable of both bridging and receiving fee tokens on a configuration basis. SwapAutomater.sol: A smart contract on the payment chain (Ethereum) in the form of a Chainlink Automation Upkeep that triggers conversion through a decentralized exchange (Uniswap), with protections in place for slippage tolerable on the Uniswap V3 routes. Reserves.sol: A smart contract on the payment chain (Ethereum) that receives LINK that was converted from fee tokens. Earmarks are set to specify how much LINK Chainlink Network service providers can withdraw.