v8.3 numPicBullet issue - needs backport

[LA15a]

docx4j version, Java used

8.3.14 + JAXB-MOXy on Java 8

The issue

Some versions of Word 365 produce a numbering.xml docx4j can’t process. Should docx4j save the resulting document, it cannot be opened by Word again.

Analysis showed the reason to be Word placing an AlternateContent inside a <w:numPicBullet>.

JaxbXmlPartXPathAware.unmarshal(InputStream, boolean), line 594, discovers the alternate content and reduces it to the fallback branch containing a drawing, ignoring the pict in the choice branch. However, the docx4j class for NumPicBullet currently only supports pict. Drawing gets ignored. On resaving, this leaves the <w:numPicBullet w:numPicBulletId="0"/> empty, corrupting the file.

Reproduction

I found this on a document after it got re-saved with Word 365. It contained an embedded image as a numbering symbol. In general, this is how to reproduce this issue: Define numbering with image as symbol. However, even Word 365 does not do this all the time, messing things up.
To speed up things I attached a ready-to-use reproduction maven project containing such a document as well as a Word 2019 counterpart without the issue.

My current solution

Can also be found and enabled in resources folder in the maven repro project

I created a copy of org.docx4j.jaxb.mc-preprocessor.xslt, then below

<xsl:template match="mc:AlternateContent">  

I added an instruction to keep the choice path of numPicBullet (-> the pict docx4j supports) instead of defaulting to fallback.

<xsl:when test="parent::w:numPicBullet">
	<xsl:variable name="message" 
		select="concat('Selecting ', name(mc:Choice/*[1]) )" />  			
	<xsl:variable name="logging" 
		select="java:org.docx4j.utils.XSLTUtils.logWarn($message)" />
	<xsl:copy-of select="mc:Choice/*"/>
</xsl:when>

Then referenced this copy inside docx4j.properties as

docx4j.jaxb.JaxbValidationEventHandler=myworkaround.xslt

Suggestion

Could this xsl:when be integrated into default mc-preprocessor.xslt?

Thank you😊

[LA15a]

Maven Repro.zip

[plutext]

Thank you for the high quality report. Following #618 this issue was fixed at ec5fed5

It needs to be back-ported to v8.3

[LA15a]

Thank you very much 😊👍

[plutext]

Backported to the 8.3 line for 8.3.16: w:numPicBullet now accepts w:drawing as well as w:pict, so the mc:Fallback that the preprocessor keeps is no longer dropped and the element no longer saves empty. Your two documents are in the test suite as the regression fixture (thanks again for the clean repro).