public void process(Metadata meta, String mimetype) throws TikaException {
        this.xmpData = TikaToXMP.convert(meta, mimetype);
    }
Converts the Metadata information to XMP. If a mimetype is provided, a specific converter can
be used, that converts all available metadata. If there is no mimetype provided or no
specific converter available a generic conversion is done which will convert only those
properties that are in known namespaces and are using the correct prefixes

@param meta     the Metadata information from Tika-core
@param mimetype mimetype information
@throws TikaException case an error occurred during conversion
tika-xmp/src/main/java/org/apache/tika/xmp/XMPMetadata.java