NVIDIA CloudXR 4.0 Server API

Gaming and Visualization Technologies XR – VR/AR/MR CloudXR (VR and AR Streaming)
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There seems to be no documentation for the native integration of CloudXR 4.0 Server into a native application. In our case, Unreal Engine.
Is this not supported in version 4.0.0?
If it is, please show us any documentation, thanks.