PluginModule.onConfigurationChanged not called when plugin config in tsconfig.json changes

TypeScript Version: 3.3.0-dev.20181208

Search Terms:

plugin configuration change
onConfigurationChanged

Expected behavior:

PluginModule.onConfigurationChanged is called when the configuration of the plugin in tsconfig.json changes. The Project already watches the tsconfig.json and therefore knows when the config of a plugin changes.

Actual behavior:

PluginModule.onConfigurationChanged is only called when the client sends a ConfigurePlugin command.

Related Issues:
#15915 is basically the same issue from 1,5 years ago. Back then it was decided this is working as intended and a plugin is responsible for watching the config file.
In the meantime onConfigurationChanged was introduced in #28106. Since ConfigurePlugin command is supposed to override any config in tsconfig.json, a plugin that watches for config file changes would need special handling to account for that fact.