Please answer a question about the following article about Umayyad Caliphate:

Many Muslims criticized the Umayyads for having too many non-Muslim, former Roman administrators in their government. St John of Damascus was also a high administrator in the Umayyad administration. As the Muslims took over cities, they left the peoples political representatives and the Roman tax collectors and the administrators. The taxes to the central government were calculated and negotiated by the peoples political representatives. The Central government got paid for the services it provided and the local government got the money for the services it provided. Many Christian cities also used some of the taxes on maintain their churches and run their own organizations. Later the Umayyads were criticized by some Muslims for not reducing the taxes of the people who converted to Islam. These new converts continues to pay the same taxes that were previously negotiated.

What tax collectors did the Umayyads often leave in place after they conquered regions?
Roman