System.Runtime.InteropServices.UnmanagedCallersOnlyAttribute
Any method marked with UnmanagedCallersOnlyAttribute can be directly called from
native code. The function token can be loaded to a local variable using the address-of operator
in C# and passed as a callback to a native method.
Optional. If omitted, the runtime will use the default platform calling convention.
Optional. If omitted, no named export is emitted during compilation.
public UnmanagedCallersOnlyAttribute()