@Nullable
  private static String validateExtrasType(@NonNull Bundle extras, @NonNull String key) {
    Object o = extras.get(key);

    if (o == null
        || o instanceof Integer
        || o instanceof Long
        || o instanceof Double
        || o instanceof String
        || o instanceof Boolean) {
      return null;
    }

    return String.format(
        Locale.US,
        "Received value of type '%s' for key '%s', but only the"
            + " following extra parameter types are supported:"
            + " Integer, Long, Double, String, and Boolean",
        o == null ? null : o.getClass(),
        key);
  }
Attempts to validate the provided RetryStrategy. If valid, null is returned. Otherwise a list
of errors will be returned.
jobdispatcher/src/main/java/com/firebase/jobdispatcher/DefaultJobValidator.java