private function validateOperands(array $values): \Illuminate\Validation\Validator 	{ 		return Validator::make([ 			'operands' => array_filter(array_keys($values), function ($value) { 				return is_string($value); 			}), 			'values' => $values, 		], [ 			'operands' => ['array'], 			'operands.*' => ['required', 'string', Rule::in($this->filter->getAvailableOperands())], 			'values' => ['array'], 			'values.*' => $this->filter->getValidationRules(), 		]); 	}