public String addClass(String content, String selector, String className) {
		return addClass(content, selector, Collections.singletonList(className));
	}
public String addClass ( String content , String selector , String className ) { return addClass ( content , selector , Collections . singletonList ( className ) ) ; }
Adds given class to the elements in HTML.

@param content
HTML content to modify
@param selector
CSS selector for elements to add the class to
@param className
Name of class to add to the selected elements
@return HTML content with modified elements. If no elements are found, the original content
is returned.
@since 1.0