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Current behavior
We are using ngx-formly in combination with the PrimenNG extension. We are trying to access certain properties of PrimeNG's p-dropdown component. We want to "styleClass" and "filter" but it seems the values are not forwarded through formly to p-dropdown.

Expected behavior

{
      key: 'marvel1',
      type: 'select',
      templateOptions: {
        label: 'Normal Select',
        styleClass: 'p-col-12',
        filter: true,
        options: [
          {label: 'Iron Man', value: 'iron_man'},
          {label: 'Captain America', value: 'captain_america'},
          {label: 'Black Widow', value: 'black_widow'},
          {label: 'Hulk', value: 'hulk'},
          {label: 'Captain Marvel', value: 'captain_marvel'},
        ],
      },
    }

This should set [styleClass]="p-col-12" and [filter]="true" on the p-dropdown component.

Minimal reproduction of the problem with instructions
https://stackblitz.com/edit/angular-gcwmbd

What is the motivation / use case for changing the behavior?

Please tell us about your environment:

• Angular version: 7.2.15

• Browser: all

• Language: [all | TypeScript X.X | ES6/7 | ES5]

• Node (for AoT issues): node --version =12.4.0