my @svg_names = ( qw/master01 master02 .../; # or whatever those names are
# … create those files ...

my $pathstr = join( '', $outputfiles, $invoice_data_ref{actual_invoice_id} );
my @cmdargs = qw/java -jar /var/ww/helper_code/svg2pdf.jar/;
push @cmdargs, "$pathstr/$_.svg" for ( @svg_names );
push @cmdargs, "$pathstr/master.pdf";