* @param request SlingHttpServletRequest which provides context to get OSGi Services
* @param filter Filter expression to filter services on "(service.property=value)"
* @return a List of Service objects
*/
public static <T> List<T> getServices(Class<T> serviceType, SlingHttpServletRequest request, String filter) {
SlingScriptHelper sling = HttpRequestUtil.getSlingScriptHelper(request);
if(sling == null) { return new ArrayList<T>(); }
return getServices(serviceType, sling, filter);
}