Instead of writing XMP metadata with a string buffer, change to use XmlWriter instead. Extract XMP metadata writing into its own class vcl::pdf::XmpMetadata. This also needs a change to the XmlWriter to not write a classic XML header: '<?xml version="1.0" ... ?>' Change-Id: I95ea0e7ba58e7c43a0c707bf9c676994210ff104 Reviewed-on: https://gerrit.libreoffice.org/c/core/+/85908 Reviewed-by: Tomaž Vajngerl <quikee@gmail.com> Tested-by: Tomaž Vajngerl <quikee@gmail.com>