OpenXML Filter: DOCX: incomplete numbering properties cause a crash

[Denis Konovalyenko]

This is a regression after the merge of the solution for issue #1313.

java.lang.NullPointerException
    at net.sf.okapi.filters.openxml.NumberingDefinition$Abstract.referencedWith(NumberingDefinition.java:140)
    at net.sf.okapi.filters.openxml.NumberingDefinition$Instance.referencedWith(NumberingDefinition.java:274)
    at net.sf.okapi.filters.openxml.NumberingDefinitions$Default.markReferencedFrom(NumberingDefinitions.java:162)
    at net.sf.okapi.filters.openxml.Block.clarifyNumberingDefinitionsWith(Block.java:166)
    at net.sf.okapi.filters.openxml.StyledTextPart.process(StyledTextPart.java:319)
    at net.sf.okapi.filters.openxml.StyledTextPart.open(StyledTextPart.java:238)
    at net.sf.okapi.filters.openxml.StyledTextPart.open(StyledTextPart.java:132)
    at net.sf.okapi.filters.openxml.OpenXMLFilter.nextInDocument(OpenXMLFilter.java:455)
    at net.sf.okapi.filters.openxml.OpenXMLFilter.next(OpenXMLFilter.java:260)
    at net.sf.okapi.filters.openxml.OpenXMLFilter.next(OpenXMLFilter.java:269)

A sample document for triggering the error is attached.

[Denis Konovalyenko]

Solution details:

1. If numbering properties do not contain a reference to a number, they are ignored.
2. If numbering properties do not reference a numbering level, a “0” value is assumed by default.

‌

[Denis Konovalyenko]

A related pull request #745 was merged.