Based on: https://android.googlesource.com/platform/packages/apps/ExactCalculator/+/8c43f06/src/com/android/calculator2/AlertDialogFragment.java

Base class for configuration activity. A configuration activity is started when user wishes to configure the selected plugin. To create a configuration activity, extend this class, implement abstract methods, invoke saveChanges(options) and discardChanges() when appropriate, and add it to your manifest like this:

Base class for a help activity. A help activity is started when user taps help when configuring options for your plugin. To create a help activity, just extend this class, and add it to your manifest like this:

HelpCallback is an HelpActivity but you just need to produce a CharSequence help message instead of having to provide UI. To create a help callback, just extend this class, implement abstract methods, and add it to your manifest following the same procedure as adding a HelpActivity.

Base class for a native plugin provider. A native plugin provider offers read-only access to files that are required to run a plugin, such as binary files and other configuration files. To create a native plugin provider, extend this class, implement the abstract methods, and add it to your manifest like this:

Activity that's capable of getting EXTRA_OPTIONS input.

Helper class to provide relative paths of files to copy.

The contract between the plugin provider and host. Contains definitions for the supported actions, extras, etc.

Helper class for processing plugin options.