The english translation of Article 458 of Indonesian Law No. 1/2009 reads:
The airspace of the Republic of Indonesia, whose navigation services are delegated to other countries under an agreement shall be evaluated and serviced by the service provider of the air navigation service no later than 15 (fifteen) years after the Act becomes effective.
In other words, Indonesian law calls for all Indonesian airspace to be serviced by Indonesia by 2024.
Other reading:
The Riau Islands airspace control issue is a S’pore target that Indonesian politicians can’t resist
Report that Singapore has no objections to Indonesian plans to manage Riau airspace inaccurate: MFA
Safety first in managing airspace
https://www.rsis.edu.sg/wp-content/u...03/CO16068.pdf
INDONESIA AIR TRAFFIC SERVICES (ATS) READINESS AND STRATEGIC PLANS FOR TAKING OVER AIRSPACE AND IMPROVING THE SERVICE