fix import resolution for Object String (and other) member class clashes, javadoc fix, disable maven-build-cache

[davidmoten]

• replace @link in openapi descriptions with @code (because those links don't work necessarily)
• skip spotbugs in test-all.sh
• disable maven-build-cache

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 92.94118% with 6 lines in your changes are missing coverage. Please review.

Project coverage is 69.06%. Comparing base (93dd4e5) to head (e862797).

Files	Patch %	Lines
...dmoten/oa3/codegen/generator/internal/Imports.java	91.78%	0 Missing and 6 partials :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #159 +/- ## ============================================ + Coverage 69.00% 69.06% +0.05% - Complexity 1042 1043 +1 ============================================ Files 84 84 Lines 4436 4441 +5 Branches 604 606 +2 ============================================ + Hits 3061 3067 +6 Misses 1170 1170 + Partials 205 204 -1 ```

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