class MigrateSource

class MigrateSource extends Plugin implements MultipleProviderAnnotationInterface {
    
    /**
     * A unique identifier for the process plugin.
     *
     * @var string
     */
    public $id;
    
    /**
     * Whether requirements are met.
     *
     * @var bool
     */
    public $requirements_met = TRUE;
    
    /**
     * Identifies the system providing the data the source plugin will read.
     *
     * The source plugin itself determines how the value is used. For example,
     * Migrate Drupal's source plugins expect source_module to be the name of a
     * module that must be installed and enabled in the source database.
     *
     * @var string
     *
     * @see \Drupal\migrate_drupal\Plugin\migrate\source\DrupalSqlBase::checkRequirements
     */
    public $source_module;
    
    /**
     * Specifies the minimum version of the source provider.
     *
     * This can be any type, and the source plugin itself determines how it is
     * used. For example, Migrate Drupal's source plugins expect this to be an
     * integer representing the minimum installed database schema version of the
     * module specified by source_module.
     *
     * @var mixed
     */
    public $minimum_version;
    
    /**
     * {@inheritdoc}
     */
    public function getProvider() {
        if (isset($this->definition['provider'])) {
            return is_array($this->definition['provider']) ? reset($this->definition['provider']) : $this->definition['provider'];
        }
        return FALSE;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getProviders() {
        if (isset($this->definition['provider'])) {
            // Ensure that we return an array even if
            // \Drupal\Component\Annotation\AnnotationInterface::setProvider() has
            // been called.
            return (array) $this->definition['provider'];
        }
        return [];
    }
    
    /**
     * {@inheritdoc}
     */
    public function setProviders(array $providers) {
        $this->definition['provider'] = $providers;
    }

}