private boolean isPlaceholder(HSLFShape shape) {
        return shape instanceof SimpleShape && ((SimpleShape) shape).isPlaceholder();
    }
This is the catch-all for embedded objects.  If we didn't come across
them in the shapes in the slides, headers/footers, etc, try to
extract them here.
tika-parsers/tika-parsers-standard/tika-parsers-standard-modules/tika-parser-microsoft-module/src/main/java/org/apache/tika/parser/microsoft/HSLFExtractor.java