public function addPlugin(Plugin $plugin): Builder
    {
        $this->plugins[]          = $plugin;
        $this->httpClientModified = true;

        return $this;
    }
public function addPlugin(Plugin $plugin): Builder
    {
        $this->plugins[]          = $plugin;
        $this->httpClientModified = true;

        return $this;
    }
public function addPlugin ( Plugin $ plugin ) : Builder { $ this -> plugins [ ] = $ plugin ; $ this -> httpClientModified = true ; return $ this ; }
Add a new plugin to the end of the plugin chain.

@param Plugin $plugin

@return Builder
Add a new plugin to the end of the plugin chain .