code: public static boolean optBoolean(@Nullable Bundle bundle, @Nullable String key, boolean fallback) {
          if (bundle == null) {
              return fallback;
          }
          return bundle.getBoolean(key, fallback);
      }
docs: Returns a optional boolean value. In other words, returns the value mapped by key if it exists and is a boolean.
  The bundle argument is allowed to be {@code null}. If the bundle is null, this method returns a fallback value.
  @param bundle a bundle. If the bundle is null, this method will return a fallback value.
  @param key a key for the value.
  @param fallback fallback value.
  @return a boolean value if exists, fallback value otherwise.
  @see android.os.Bundle#getBoolean(String, boolean)