code: public String getAsStringWithDefault(String key, String defaultValue) {
  		Object value = getAsObject(key);
  		return StringConverter.toStringWithDefault(value, defaultValue);
  	}
docs: Converts map element into a string or returns default value if conversion is
  not possible.
  
  @param key          a key of element to get.
  @param defaultValue the default value
  @return string value of the element or default value if conversion is not
  supported.
  
  @see StringConverter#toStringWithDefault(Object, String)