code: public Kafka startFromSpecificOffset(int partition, long specificOffset) {
  		this.startupMode = StartupMode.SPECIFIC_OFFSETS;
  		if (this.specificOffsets == null) {
  			this.specificOffsets = new HashMap<>();
  		}
  		this.specificOffsets.put(partition, specificOffset);
  		return this;
  	}
docs: Configures to start reading partitions from specific offsets and specifies the given offset for
  the given partition.
  
  @param partition partition index
  @param specificOffset partition offset to start reading from
  @see FlinkKafkaConsumerBase#setStartFromSpecificOffsets(Map)