Entity/Form.php
public function getField($key)
    {
        foreach ($this->fields as $field) {
            if ($field->getKey() == $key) {
                return $field;
            }
        }
    }
public function getField($key)
    {
        foreach ($this->fields as $field) {
            if ($field->getKey() == $key) {
                return $field;
            }
        }
    }
Get field by key.

@param string $key

@return FormField|null