what's the PlexusContainer?

[陈思淼]

I want to define a new packaging type called jcar to package my own project.
i read the maven source , and find the maven-core use
PlexusContainer.lookup() to find a new LifecycleMapping
to, can anybody tell me how that process works? and where to download
PlexusContainer source code so i can read
the detail of it.
thank you!