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