Constructs a FormatterPluginManager object.
\Traversable $namespaces: An object that implements \Traversable which contains the root paths keyed by the corresponding namespace to look for plugin implementations,
public function __construct(\Traversable $namespaces) {
$annotation_namespaces = array(
'Drupal\\field\\Annotation' => $namespaces['Drupal\\field'],
);
$this->discovery = new AnnotatedClassDiscovery('field/formatter', $namespaces, $annotation_namespaces, 'Drupal\\field\\Annotation\\FieldFormatter');
$this->discovery = new AlterDecorator($this->discovery, 'field_formatter_info');
$this->discovery = new CacheDecorator($this->discovery, 'field_formatter_types', 'field');
}