It would be useful if the plugin allowed multiple resources to be locked on each build referenced by different resource group labels.

This is the same as requested here:

https://github.com/jenkinsci/lockable-resources-plugin/issues/23

Also, it would be better if it was possible to specify a quantity of resources required for each resource group.

Similar work seems to have been done in this pull request:

https://github.com/jenkinsci/lockable-resources-plugin/pull/38