* 3.0.x. Historically, it logged and ignored a second addition of the same g/a/v/c/t. Now it replaces the file for
     * the artifact, so that plugins (e.g. shade) can change the pathname of the file for a particular set of
     * coordinates.
     *
     * @param artifact the artifact to add or replace.
     * @deprecated Please use {@link MavenProjectHelper}

        // effective model.
        //
        // As of 3.4, the model version is mandatory even in raw models. The XML element still is optional in the
        // XML schema and this will not change anytime soon. We do not want to build effective models based on
        // models without a version starting with 3.4.
        validateStringNotEmpty("modelVersion", problems, Severity.ERROR, Version.V20, m.getModelVersion(), m);