Your code works just fine for me, except that I had to define a return_param_name method to return its own first argument. Assuming that method doesn't do anything bizarre, your code should work as given. Here's my complete output:

ARRAY------>Blocking       : Blocking
------>Priority       : P01
$VAR1 = {
          'Blocking' => [
                          'Blocking'
                        ],
          'Priority' => [
                          'P01'
                        ]
        };
$VAR1 = \[
            {
              'content' => 'Blocking',
              'type' => 'Blocking'
            },
            {
              'content' => 'P01',
              'type' => 'Priority'
            }
          ];
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