src/Resource/AbstractResource.php
public function arrayKeyExists($key)
    {
        if (array_key_exists($key, $this->content)) {
            return true;
        }

        $parts = explode('.', $key);
        $arr = $this->content;
        foreach ($parts as $part) {
            if (!is_array($arr) || !array_key_exists($part, $arr)) {
                return false;
            }

            $arr = $arr[$part];
        }

        return true;
    }
public function arrayKeyExists($key)
    {
        if (array_key_exists($key, $this->content)) {
            return true;
        }

        $parts = explode('.', $key);
        $arr = $this->content;
        foreach ($parts as $part) {
            if (!is_array($arr) || !array_key_exists($part, $arr)) {
                return false;
            }

            $arr = $arr[$part];
        }

        return true;
    }
Port of array_key_exists to \ArrayAccess

@param mixed $key The key to check if exists

@return bool Does the key exist