As a adminstrator of JIRA,
When doing a single project import,
JIRA needs to import all extra greenhopper version data
so that my report data and graphs are not unuseable.
Performing a single project import does not import green hopper aditional attributes on versions. Specically it does not respect the heirachy and the start/end/release dates on versions.
This is very furstrating when importing a single project, as manually entering this data after the import is slow and painful (as you have to do it on the agile screen, as not all details are setable on the versions screen). Any extra custom data attributes used by plugins should be imported as some of this data is critical to the usefulness of JIRA.
The lack of this data ruins reports and graphs that can be obtained on the interface.