code: public FlinkKafkaConsumerBase<T> setStartFromEarliest() {
  		this.startupMode = StartupMode.EARLIEST;
  		this.startupOffsetsTimestamp = null;
  		this.specificStartupOffsets = null;
  		return this;
  	}
docs: Specifies the consumer to start reading from the earliest offset for all partitions.
  This lets the consumer ignore any committed group offsets in Zookeeper / Kafka brokers.
  
  <p>This method does not affect where partitions are read from when the consumer is restored
  from a checkpoint or savepoint. When the consumer is restored from a checkpoint or
  savepoint, only the offsets in the restored state will be used.
  
  @return The consumer object, to allow function chaining.