code: public static void removeFileOpener(ServletContext servletContext, String ... extensions) {
  		synchronized(fileOpenersLock) {
  			@SuppressWarnings("unchecked")
  			Map<String,FileOpener> fileOpeners = (Map<String,FileOpener>)servletContext.getAttribute(FILE_OPENERS_REQUEST_ATTRIBUTE_NAME);
  			if(fileOpeners != null) {
  				for(String extension : extensions) {
  					fileOpeners.remove(extension);
  				}
  				if(fileOpeners.isEmpty()) {
  					servletContext.removeAttribute(FILE_OPENERS_REQUEST_ATTRIBUTE_NAME);
  				}
  			}
  		}
  	}
docs: Removes file openers.
  
  @param  extensions  The simple extensions, in lowercase, not including the dot, such as "dia"