That wasn't specifically set out in black and white iirc but even if not, it's a pretty safe assumption. In their submission to CAS, City talked about the 'accruals basis' of accounting, which is separate to the cash payments. That means if Etihad contract to pay us £60m a year over 10 years, we'll record £60m a year in the accounts, regardless of whether the cashflow is £60m a year or not.
If Etihad paid us £200m in year one, we'd still show that as £60m revenue in the P&L account, with £140m as deferred revenue in the balance sheet. If they paid us nothing the following year, we'd again show £60m revenue, but with deferred revenue of £80m.
So when Harris was going on about us under-stating the Etihad revenue, when he added up three years cash receipts and divided by three, he clearly had no idea about accruals accounting. The timing of the cashflow is irrelevant.