FOR INTERNAL USE ONLY. This is a unique identifier assigned to each
            resource to allow Maven to merge changes to this resource that take
            place during the execution of a plugin. This field must be managed
            by the generated parser and formatter classes in order to allow it
            to survive model interpolation.
          </description>
          <type>String</type>

     * during metadata retrieval.
     */
    int VALIDATION_LEVEL_MINIMAL = 0;

    /**
     * Denotes validation as performed by Maven 2.0. This validation level is meant as a compatibility mode to allow
     * users to migrate their projects.
     */
    int VALIDATION_LEVEL_MAVEN_2_0 = 20;

    /**
     * Denotes validation as performed by Maven 3.0. This validation level is meant for existing projects.
     */

                    Severity.ERROR,
                    Version.V20,
                    repository.getUrl(),
                    null,
                    repository)) {
                // only allow ${basedir} and ${project.basedir}
                Matcher m = EXPRESSION_NAME_PATTERN.matcher(repository.getUrl());
                while (m.find()) {