At the moment the manifest creation relies on the packages exported by the bundles installed on the OSGi platform. This can be inefficient especially if the test doesn't actually uses all the classes or the bundles themselves (they are dependencies).
A faster and more efficient way would be to use a bytecode library (i.e. ASM) to inspect the import packages for the running test and use only these.
There will be no versioning information but that's okay since it's a test environment and it's likely only version of a certain package will be present - if more are required, then there is always the static manifest creation.