Inconsistency in SITL JSON interface example

https://github.com/ArduPilot/ardupilot/blob/4088ab91c62d7ad1f4472df461061ff84ede1433/libraries/SITL/examples/JSON/C%2B%2B/minimal.cpp#L71-L76

In the example above the IMU is supposed to have a FRD (x-axis pointing forward, y-axis pointing right and z-axis pointing down) orientation. In this case the expected measured acceleration in the line above should be `9.81` rather than `-9.81`. Is this correct or did I understand this incorrectly?

Inspect libraries/SITL/examples/JSON/C++/minimal.cpp at lines 71-76. Verify the FRD orientation convention against the acceleration value shown in the example and confirm whether the sign is inconsistent. Done means the example and its stated orientation agree, with the issue question resolved.

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