Understanding gas calculations: How is `paymasterVerificationGasLimit` estimated?

[matthiasgeihs]

Hey, I'm trying to understand how gas estimations work. In particular, looking at paymasterVerificationGasLimit.

What I do understand: EntryPointSimulations.sol is used to simulate operations and thereby measure gas.

What I don't understand: The return type struct ExecutionResult of simulateHandleOP does not include paymasterVerificationGasLimit, however, the EntryPointV07SimulationsAbi does have this field in the return value of this function (see here).

How is that possible? And how is that value calculated on the contract side?