public SubClass shouldBootstrap() {
    this.isBootstrapOptional = Optional.of(true);
    return (SubClass) this;
  }
If set, this stream will be processed as a bootstrap stream. This means that every time a Samza container
starts up, this stream will be fully consumed before messages from any other stream are processed.

@return this input descriptor
samza-api/src/main/java/org/apache/samza/system/descriptors/InputDescriptor.java