code: public String getString(String key, String defaultValue) {
          return PersistableBundleCompat.getString(bundle, key, defaultValue);
      }
docs: Returns the value associated with the given key, or defaultValue if no mapping of the desired
  type exists for the given key or if a null value is explicitly associated with the given
  key.
  
  @param key          a String, or null
  @param defaultValue Value to return if key does not exist or if a null value is associated
  with the given key.
  @return the String value associated with the given key, or defaultValue if no valid String
  object is currently mapped to that key.