docs: public static String lookupEncoding(String encoding, String fallback) {
  
          String result = m_encodingCache.get(encoding);
          if (result != null) {
              return result;
          }
  
          try {
              result = Charset.forName(encoding).name();
              m_encodingCache.put(encoding, result);
              return result;
          } catch (Throwable t) {
              // we will use the default value as fallback
          }
  
          return fallback;
      }