It's a sample code to integrate Azure Function with App Insights in Azure China.
As Azure App Insights requires a change to point to Azure China Endpoint, we need to override the Telemetry Channel for Azure Function manully.
Here, I have create a new file named Startup.cs. Azure Function is built as ASP.NET website, so that we can create a Startup.cs as well to change the behaviors.
In the Startup.cs, some codes have been appended to override the configuration.
Check the Configure for your reference.
Support for Application Insights in the Azure Government Cloud
Azure China IP addresses and Domains used by Application Insights and Log Analytics