public function getFieldInputSpecification($field)
    {
        if (!$this->hasField($field)) {
            return [];
        }

        if (!isset($this->fields[$field]['__filter__'])) {
            $this->fields[$field]['__filter__'] = $this->copyArrayValues(
                $this->fields[$field],
                [
                    'input_filter' => [],
                    'required',
                ]
            );
        }

        return $this->fields[$field]['__filter__'];
    }