code: public static boolean addStaticExtension(String extension) {
      	if(AssertUtils.isEmpty(extension)) {
      		return false;
      	}
      	
      	if(!extension.startsWith(".")) {
      		extension = "." + extension;
      	}
      	
      	extension = extension.toLowerCase();
      	
      	return STATIC_RESOURCE_EXTENSIONS.add(extension);
      }
docs: Add the given extension to the list of static resources.
  
  @param extension
  the extension to add
  
  @return <code>true</code> if extension was added, <code>false</code>
  otherwise