Need Unity as a library docs/sample

Need documentation or a sample for using Crashlytics from both Unity C# code and platform-native (Objective-C or Java) code in a Unity-as-a-library app.

Given a Unity-as-a-library app where the platform-native code is already making extensive use of Crashlytics, establishes the necessary app registration, and provides the necessary core Crashlytics libraries, we _also_ want to use Crashlytics APIs from Unity C# code,

We could make calls to platform native code to call Crashlytics indirectly, but Crashlytics.LogException(Exception) is of particular interest and does not lend itself to this approach.