src/Application/Config.php
public function merge(Config $config): Config
    {
        $this->config = array_merge_recursive($this->config, $config->config);

        return $this;
    }
public function merge(Config $config): Config
    {
        $this->config = array_merge_recursive($this->config, $config->config);

        return $this;
    }
Merges one instance of Config class into current one and
returns current instance.

@param Config $config
@return Config