code: public boolean getBoolean(String key, boolean defaultValue) {
      Object value = get(key);
      if (value instanceof Boolean) {
        return (boolean) value;
      } else if (value instanceof String) {
        return Boolean.valueOf((String) value);
      }
      return defaultValue;
    }
docs: Returns the value mapped by {@code key} if it exists and is a boolean or can be coerced to a
  boolean. Returns {@code defaultValue} otherwise.