@sebikeller could I ask you to write a test that covers this change?

@sebikeller - I've just tried adding some integration tests to master that add white spaces to values and notes at beginning and endings of multiple lines and I can't reproduce your problem.
If you could add an integration test that fails without your change we can review this PR better.
Thanks,

I agree, with an integration test, its not possible to reproduce the problem.

But if you open the generated file with excel, you'll see the difference.

branch master

exceljs-master.xlsx

applied pr

exceljs-pr896.xlsx

Recreating the file in excel, following xml can be extracted:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?><commentsxmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main">  <authors>...</authors>  <commentList>    <commentref="A1"authorId="0"shapeId="0">      <text>        <r>          <rPr>            <b/>          </rPr>          <t>First Line:</t>        </r>        <r>          <txml:space="preserve"></t>        </r>        <r>          <txml:space="preserve">Second Line</t>        </r>        <r>          <txml:space="preserve">Third Line</t>        </r>        <r>          <t>Last Line</t>        </r>      </text>    </comment>  </commentList></comments>

Since we cant recreate it with an integration test, it actually means, that the exceljs parser has difference with that of excel.
So you might consider adding atrim() to text values unlessxml:space="preserve" is set.

@sebikeller - agreed! I'll add a unit test on the strings xforms to keep a check on this...