Single output not referencing full output on export

https://github.com/seek4science/seek/issues/904#issuecomment-1044431205 has an example that is not super-readable.

Start with the example linked in the issue comment and inspect how gxformat2 handles single-output export compared with the full output. Identify the relevant export entry point and tests, then define completion by making the exported reference match the intended full-output behavior described by the example.

Written by the indexing model from the issue text.