companions property
The registries that come with this one, found by PluginHost.registry
as if each had been handed to the host itself.
How one handle brings a subsystem's several registries: a renderer's
render steps bring its lighting models, its light types and its
draw-list hooks, so an engine that hands the host
renderer.renderSteps gives a plugin all of them. None by default.
Implementation
Iterable<PluginRegistry> get companions => const <PluginRegistry>[];