laravel required if not code example

Example 1: laravel required if

"sale_price" => "required_if:list_type,==,selling"

Example 2: field not required validation laravel

$this->validate($request, [
	"field_nullable" => "nullable"
]

Example 3: required_if laravel

public function rules()
 {
    return [
      'reclamo_procede'  => 'max:1',             
      'solucion_minutos' => 'required_if:reclamo_procede,==,si', 
    ];
 }