And what’s worse, the scanner errors out, rather than just giving a warning, if (one of) the path(s) defined for sonar.testExecutionReportPaths does not exist. And, contrary to all(?) other path properties it does not support wildcards. See Sonar-scanner doesn't support wildcards in sonar.testExecutionReportPaths.
If you force us to define sonar.testExecutionReportPaths at root level it should be possible to enter wildcarded paths that may or may not exist in all Maven (sub) modules.