use XML::Simple;
use Data::Dumper;

my $x =<<EOF;
   <stuff name="me">
    <obj class="myclass">
        <set name="key1">a</set>
        <set name="key2"></set>
    </obj>
    <obj class="myclass">
        <set name="key1">a</set>
        <set name="key2">b</set>
    </obj>
</stuff>
EOF

$x = XMLin(
    $x,
    #SuppressEmpty => '',
    ForceArray => 1,
    ContentKey => '-content',
);
print Dumper(\$x);


$VAR1 = \{
            'obj' => [
                     {
                       'class' => 'myclass',
                       'set' => {
                                'key2' => {},
                                'key1' => {
                                          'content' => 'a'
                                        }
                              }
                     },
                     {
                       'class' => 'myclass',
                       'set' => {
                                'key2' => 'b',
                                'key1' => 'a'
                              }
                     }
                   ],
            'name' => 'me'
          };

##</code><code>##

'key2' => 'b',
'key1' => 'a'