public Set<String> addMapping(final String... urlPatterns) {
        DeploymentInfo deploymentInfo = deployment.getDeploymentInfo();
        final Set<String> ret = new HashSet<>();
        final Set<String> existing = new HashSet<>();
        for (ServletInfo s : deploymentInfo.getServlets().values()) {
            if (!s.getName().equals(servletInfo.getName())) {
                existing.addAll(s.getMappings());
            }
        }
        for (String pattern : urlPatterns) {
            if (existing.contains(pattern)) {
                ret.add(pattern);
            }
}

    public Set<String> addMapping(String... urlPatterns) {
        Set<String> conflicts = new HashSet<String>();
        if (!((Context) wrapper.getParent()).isStarting()) {
            throw MESSAGES.cannotAddServletRegistrationAfterInit(((Context) wrapper.getParent()).getPath());
        }
        if (urlPatterns == null || urlPatterns.length == 0) {
            throw MESSAGES.invalidServletRegistrationArguments();
        }
        for (String urlPattern : urlPatterns) {
			Context context = ((Context) wrapper.getParent());
            String wrapperName = context.findServletMapping(urlPattern);
            if (wrapperName != null) {
                Wrapper servletWrapper = (Wrapper) context.findChild(wrapperName);
                if (servletWrapper.isOverridable()) {
                    // Some Wrappers (from global and host web.xml) may be
                    // overridden rather than generating a conflict
                    context.removeServletMapping(urlPattern);
                } else {
                    conflicts.add(urlPattern);
                }
			}
        }