code: public void putMeta(String key, Object value) {
  		manifest.getMainAttributes().putValue(key, ConverterRegistry.getConverter().asString(value));
  	}
docs: Put meta data to this archive manifest. If <code>key</code> already exists is overridden. Meta <code>value</code> is
  converted to string and can be any type for which there is a {@link Converter} registered.
  
  @param key meta data key,
  @param value meta data value.