Which mavlink version is used by latest PX4?

I have download the latest PX4 for development, but when I read it’s mavlink source code, I found that in mavlink_messages.cpp, there is the mavlink 2.0 message formatters implementation, at the same time, in mavlink_main.cpp, there is the mavlink 1.0 protocol implementation. So, I confused about which mavlink version is used by PX4, 1 or 2, or 1’s protocol and 2’s message formatters?

By default V1 is used. Can switch to V2 if received V2 packets from external devices.

Ok, thank you very much