*/
    internal var lockingSourceCount = 0

    /** The sequence number of the most recently committed edit to this entry. */
    internal var sequenceNumber: Long = 0

    init {
      // The names are repetitive so re-use the same builder to avoid allocations.
      val fileBuilder = StringBuilder(key).append('.')
      val truncateTo = fileBuilder.length
      for (i in 0 until valueCount) {