String getInitials(String id) {
            if (id == null) {
                return null;
            }
            return initialMap.get(id);
        }
In PowerPoint files, slides have things embedded in them,
and slide drawings which have the images
tika-parsers/tika-parsers-standard/tika-parsers-standard-modules/tika-parser-microsoft-module/src/main/java/org/apache/tika/parser/microsoft/ooxml/SXSLFPowerPointExtractorDecorator.java