code: public static boolean includes(final Language language1, final Language language2) {
  		if(language1==null || language2==null) {
  			return false;
  		}
  		if(language1.isWildcard()) {
  			return true;
  		}
  		if(language2.isWildcard()) {
  			return false;
  		}
  		return
  			language1.primaryTag().equals(language2.primaryTag()) &&
  			(language1.subTag().isEmpty() || language1.subTag().equals(language2.subTag()));
  	}
docs: Implements Basic Filtering matching algorithm defined in
  <a href="https://tools.ietf.org/html/rfc4647#section-3.3.1">Section
  3.3.1</a> of the <b>Matching of Language Tags</b> (BCP 47)
  
  @param language1
  the including language
  @param language2
  the language that will be checked for inclusion
  @return true, if the {@code language1} includes {@code language2}
  attending to the aforementioned algorithm.