Is there an easy way to generate the aggregate report?

Unfortunately Maven's internal support for report aggregation is rather poor so it does have a number of limitations. Foremost the aggregate report is generated before the child reports, so you must re-run the JavaNCSS report after the children have generated, like this:

mvn clean site (generate the site for every module recursively)

mvn javancss:report (re-run the JavaNCSS report recursively so the aggregate report works)

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