code: public static void throwIfRequestingUnknownFeatures(HColumnDescriptor columnDescriptor) {
      List<String> unknownFeatures = getUnknownFeatures(columnDescriptor);
      if (!unknownFeatures.isEmpty()) {
        String featureString = String.format(
            "Unknown configuration options: [%s]",
            Joiner.on(", ").join(unknownFeatures));
        throw new UnsupportedOperationException(featureString);
      }
    }
docs: Throw an {@link java.lang.UnsupportedOperationException} if the column descriptor cannot be adapted due
  to it having unknown configuration keys.
  
  @param columnDescriptor a {@link org.apache.hadoop.hbase.HColumnDescriptor} object.