Justified text layout becomes ragged when soft hyphens present

When soft hyphens (0x00ad) are included in a QTextDocument in QTextBlocks with alignment = Qt::AlignJustify, the alignment is NOT fully justified.

This behaviour can be seen using the demo 'Text Edit' application by opening an html file containing justified paragraphs and soft hyphens.

Although the screen rendering may be 'acceptable', the ragged justification can be quite noticeable in exported pdf.

An example html file is attached, along with the pdf. Note also the absence of a hyphen at the end of the third paragraph in the pdf, although it is in the html.