validateVersion(
                            prefix, "version", problems, errOn30, Version.V20, d.getVersion(), d.getManagementKey(), d);

                    /*
                     * Extensions like Flex Mojos use custom scopes like "merged", "internal", "external", etc. In
                     * order to not break backward-compat with those, only warn but don't error out.
                     */

            String defaulModelId = DefaultLifecycleRegistry.DEFAULT_LIFECYCLE_MODELID;
            List<String> unversionedPlugins = buildPlan
                    .allSteps()
                    .flatMap(step -> step.mojos.values().stream().flatMap(map -> map.values().stream()))
                    .map(MojoExecution::getPlugin)
                    .filter(p -> p.getLocation("version") != null