yii\elasticsearch\QueryBuilder::buildNotCondition PHP Method

    private function buildNotCondition($operator, $operands)
    {
        if (count($operands) != 1) {
            throw new InvalidParamException("Operator '{$operator}' requires exactly one operand.");
        }
        $operand = reset($operands);
        if (is_array($operand)) {
            $operand = $this->buildCondition($operand);
        }
        return [$operator => $operand];
    }