DB<100> use JSON

  DB<101> $hoH = {
             nested => { crossReference => 42, incidentAbstract => "string" },
           }

  DB<102> $str = (new JSON)->pretty(1)->encode($hoH)
{
   "nested" : {
      "incidentAbstract" : "string",
      "crossReference" : "42"
   }
}

  DB<103> %translate= ( 
                      'crossReference' => 'cross_reference' ,
                      "incidentAbstract" => 'abstract',
                      )

  DB<104> $or_keys = join "|", keys %translate
 => "incidentAbstract|crossReference"

  DB<105> $str =~ s/^(\s+")($or_keys)("\s+:)/$1$translate{$2}$3/gm
 => 2

  DB<106> $str
{
   "nested" : {
      "abstract" : "string",
      "cross_reference" : "42"
   }
}