As the name says, this class creates a package set based on the output of
a given command. The command is run once when the set is accessed
for the first time during the current session.
Single Set Configuration
In single set configurations this class supports the following options:
command: Required. Specifies the command
that should be executed to generate the package set. It should
output a newline separated list of simple and/or versioned atoms
on stdout.