New Models from Java Sources: issue with <import implicit="true"> Follow

Hi, I am working on a generation target language named `com.dslfoundry.docx` for generating .docx files from an MPS model. It is based on the good work from the [docx4j project](https://docx4java.org/ ). My project is on [GitHub](https://github.com/DSLFoundry/mps-docxgen)

Part of the effort is to get the samples provided by the docx4j project running in MPS. The samples are provided as source code and I want to import them as source code. One issue I encountered is this.

After importing there are a number of references that have an error "out of search scope". However, you can ctrl-click on them and jump to the java stub containing the referenced item. When investigated I noticed that this java stub is not visible in the Dependencies tab of the model properties, but when peeking into the .mps file, I see that the java stub model has an <import> entry with implicit="true". Next I imported the java stub manually. This resolves the reference. Also the implicit="true" attribute is removed from the .mps file.

This issue is not blocking, it is just a nuisance, taking time to figure out and to fix. I would like to understand the following

- what does implicit="true" actually mean?

- why does "New Models from Java Sources" put it there for some models but not all?