private void addRelatedParts(PackagePart documentPart, List<PackagePart> relatedParts) {
        for (String relation : MAIN_PART_RELATIONS) {
            PackageRelationshipCollection prc = null;
            try {
                prc = documentPart.getRelationshipsByType(relation);
                if (prc != null) {
                    for (int i = 0; i < prc.size(); i++) {
                        PackagePart packagePart =
                                documentPart.getRelatedPart(prc.getRelationship(i));
                        relatedParts.add(packagePart);
                    }
                }
            } catch (InvalidFormatException e) {
                //swallow
            }
        }

    }
This returns all items that might contain embedded objects:
main document, headers, footers, comments, etc.
tika-parsers/tika-parsers-standard/tika-parsers-standard-modules/tika-parser-microsoft-module/src/main/java/org/apache/tika/parser/microsoft/ooxml/SXWPFWordExtractorDecorator.java