src/AbstractMessage.php
final public function isInMap($fieldName, $key)
    {
        if (empty($this->data[$fieldName]) || !is_array($this->data[$fieldName]) || !is_string($key)) {
            return false;
        }
        return isset($this->data[$fieldName][$key]);
    }
final public function isInMap($fieldName, $key)
    {
        if (empty($this->data[$fieldName]) || !is_array($this->data[$fieldName]) || !is_string($key)) {
            return false;
        }
        return isset($this->data[$fieldName][$key]);
    }
{@inheritdoc}