Github user kaspersorensen commented on the issue:
https://github.com/apache/metamodel/pull/194
I think our tests should cover most of the stuff, but the one thing that I
will admit was somewhat complicated was what I noted in the third commit:
> I ran into an issue that reminded me of what we saw some time back [1]
> with writing to a file-based workbook failing with message "user-mapped
> section open". I found a reasonable workaround where workbooks are being
> loaded based on their InputStream rather than their File reference
> whenever we access the workbook in an update callback.
>
> [1] https://bz.apache.org/bugzilla/show_bug.cgi?id=58480
Or in terms of testing ... It would be interesting to compare performance
and ability to do multiple inserts into the same sheet. I have a small fear
that this new approach is slower because it is instantiating the Workbook based
on `InputStream` instead of `File`. But OTOH I don't know of an alternative,
because the `File` based thing is creating file system locks that prevent those
inserts from happening without having to do very silly sleeps or something like
that.
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