Creating metadata using \hypersetup

The documentation of pdfx is pretty clear on how metadata should be inserted, see Section 2.1:

As mentioned above, standards compliant PDF documents need XMP metadata to be included. In order to create XMP in the prescribed XML format, a simple data file holding the meta information of the document needs to be created either through a program or by hand. For our purposes, we name it as \jobname.xmpdata, a simple example of which will look like the following:

    \Keywords{pdfTeX\sep PDF/X-1a\sep PDF/A-b}
    \Title{Sample LaTeX input file}
    \Author{LaTeX project team}
    \Org{TeX Users Group}