How to configure the MIGS Omnipay gateway?
I got this to work with the following meta-data file. omnipay_Migs_TwoParty.mgd.php. Since the field in the code is merchantAccessCode I changed the label for passwords to "Merchant access code'. Both the debugger and the error message show this. 

return [
 [ 
   'name' =&gt; 'OmniPay - MIGS',
   'entity' =&gt; 'payment_processor_type',
   'params' =&gt; array(
     'version' =&gt; 3,
     'title' =&gt; 'OmniPay - MIGS',
     'name' =&gt; 'Migs_TwoParty',
     'description' =&gt; 'Omnipay MIGS',
     // DO NOT CHANGE: Labels are used as Omnipay gateway properties.
    'user_name_label' =&gt; 'Merchant Id',
    'password_label' =&gt; 'Merchant access code',
    'signature_label' =&gt; 'Secure Hash',
    'class_name' =&gt; 'Payment_OmnipayMultiProcessor',
    'url_site_default' =&gt; 'http://unused.com',
    'url_api_default' =&gt; 'http://unused.com',
    'url_recur_default' =&gt; 'http://unused.com',
    'url_site_test_default' =&gt; 'http://unused.com',
    'url_recur_test_default' =&gt; 'http://unused.com',
    'url_api_test_default' =&gt; 'http://unused.com',
    'billing_mode' =&gt; 1,
    'payment_type' =&gt; 1,
    'is_recur' =&gt; 1,
   ),
 ]
];