use strict;
use warnings;
use feature 'say';
use CAM::PDF;
use XML::LibXML;

my $doc = CAM::PDF-> new( 'test.pdf' ) or die;
$doc-> cacheObjects;

while ( my ( $k, $v ) = each %{ $doc-> { objcache }}) {
    next unless $v-> { value }{ type } eq 'dictionary' and
                $v-> { value }{ value }{ StreamData };
    my $str = $doc-> decodeOne( $v-> { value }, 0 );
    my $dom = eval { XML::LibXML-> load_xml( string => $str )};
    next unless $dom;
    
# Process expected XML, skip possible others (Adobe XMP, etc.)
# ...

}