code: public void setSequenceNumber(long value) {
          Preconditions.checkState(this.sequenceNumber < 0, "Sequence Number has been previously set for this entry. Cannot set a new one.");
          Exceptions.checkArgument(value >= 0, "value", "Sequence Number must be a non-negative number.");
  
          this.sequenceNumber = value;
      }
docs: Sets the Sequence Number for this operation, if not already set.
  
  @param value The Sequence Number to set.
  @throws IllegalStateException    If the Sequence Number has already been set.
  @throws IllegalArgumentException If the Sequence Number is negative.