code: public static PushSubscription fromString(String str) {
          if (str == null || str.isEmpty()) {
              throw new IllegalArgumentException("Cannot create a stream from an empty or null string");
          }
          PushSubscription stream = new PushSubscription();
          stream.id = str;
          return stream;
      }
docs: /*
  Create a {@link PushSubscription} instance containing only an id
  
  @param str the ID obtained from DataSift for creating a push subscription
  @return an instance which can be used by the client