} else {
            if (getLog().isDebugEnabled()) {
                getLog().debug("project.build.outputTimestamp = \"" + outputTimestamp + "\" => "
                        + new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssXXX").format(timestamp));
            }

            // check if timestamp well defined in a project from reactor
            boolean parentInReactor = false;
            MavenProject reactorParent = project;
            while (reactorProjects.contains(reactorParent.getParent())) {
                parentInReactor = true;
                reactorParent = reactorParent.getParent();
            }
            String prop = reactorParent.getOriginalModel().getProperties().getProperty("project.build.outputTimestamp");
            if (prop == null) {
                getLog().error("project.build.outputTimestamp property should not be inherited but defined in "
                        + (parentInReactor ? "parent POM from reactor " : "POM ") + reactorParent.getFile());