Resolve a part name against the table (ECMA-376 Part 2 §10.1.2.4): an
exact <Override PartName> match wins; otherwise the <Default Extension> for the part's OPC extension applies; null when neither
covers the part. Both the PartName and the path are compared in their
canonicalPartName form.
Resolve a part name against the table (ECMA-376 Part 2 §10.1.2.4): an exact
<Override PartName>match wins; otherwise the<Default Extension>for the part's OPC extension applies;nullwhen neither covers the part. Both the PartName and the path are compared in their canonicalPartName form.