docs: @Nonnull
    public QValue getQValueOfLanguage (@Nonnull final String sLanguage)
    {
      ValueEnforcer.notNull (sLanguage, "Language");
  
      // Find language direct
      QValue aQuality = m_aMap.get (_unify (sLanguage));
      if (aQuality == null)
      {
        // If not explicitly given, check for "*"
        aQuality = m_aMap.get (AcceptLanguageHandler.ANY_LANGUAGE);
        if (aQuality == null)
        {
          // Neither language nor "*" is present
          // -> assume minimum quality
          return QValue.MIN_QVALUE;
        }
      }
      return aQuality;
    }