Everything seems to work fine but the inline comments in the Json structures are missing. Mind that Json documentation is a PRO feature.
If your Data Transfer Objects are in an external dependency, Miredot cannot read the Javadoc because it simply is not there. Javadoc is thrown away at compilation.
If you have access to the sources, you can still get the documentation by telling Miredot where it can find the sources.
If you still don't get any documentation, you might want to try setting the file encoding used by Maven/Gradle to UTF8.
Just add -Dfile.encoding=UTF-8 when running Maven/Gradle or add this to the MAVEN_OPTS / GRADLE_OPTS.