nextOffset(topic, partition) {
    if (!this.resolvedOffsets[topic][partition]) {
      this.resolvedOffsets[topic][partition] = this.committedOffsets()[topic][partition]
    }

    let offset = this.resolvedOffsets[topic][partition]
    if (isInvalidOffset(offset)) {
      offset = '0'
    }

    return Long.fromValue(offset)
  }
@param {string} topic
@param {number} partition
@returns {Long}