Fix handling of incomplete touching inners

[tyrasd]

Description

Fixes a bug which caused an infinite loop in the cutAtSement method (used in mergeTouchingRings routine) because it is called with non-closed linestrings instead of rings. Fixed by making sure that buildRings does only return valid rings.

This has the side effect that some errorneous multipolygons now get "cleaned" up slightly into (smaller) polygons, where they were returned as GeometryCollections before (prior to 0.6.0). But since the old (buffer(0), see #249) implementation also had similar side effects, I see no major harm in this change.

Checklist

• My code follows the code-style rules, and I have checked on the static analyses and benchmark (if applicable) results
• I have commented my code
• I have written javadoc (required for public methods)
• I have added sufficient unit tests
• I have made corresponding changes to the documentation
• I have updated the CHANGELOG.md
• I have adjusted the examples or created an issue in the corresponding repository
• I have adjusted the benchmark or created an issue in the corresponding repository

[joker234]

Is the Milestone 0.7 fitting to this issue even tough we want to fix that directly for the 0.6 version?

[tyrasd]

Is the Milestone 0.7 fitting to this issue even tough we want to fix that directly for the 0.6 version?

I wasn't super sure about that either, but adding it to the 0.6 milestone seemed "wrong" because it's already closed; maybe not adding it to any milestone would be better? My thinking was: ok, we fix this for the current next version (0.7, indicated by the milestone) and additionally backport it as well (to 0.6, indicated by the priority:high label). 🤔

[joker234]

Is the Milestone 0.7 fitting to this issue even tough we want to fix that directly for the 0.6 version?

I wasn't super sure about that either, but adding it to the 0.6 milestone seemed "wrong" because it's already closed; maybe not adding it to any milestone would be better? My thinking was: ok, we fix this for the current next version (0.7, indicated by the milestone) and additionally backport it as well (to 0.6, indicated by the priority:high label). 🤔

I was thinking about not adding it to any milestone would be okay. But keeping it in 0.7 is okay as well.