Solarium throws exceptions when server is named "localhost"

It seems like solarium OOTB sets up a default solr instance on localhost:8983 and when you come to add a server in search_api it bails with;

Solarium\Exception\InvalidArgumentException: An endpoint must have a unique key in Solarium\Core\Client\Client->addEndpoint() (line 300 of /xxx/modules/contrib/search_api_solr/vendor/solarium/solarium/library/Solarium/Core/Client/Client.php).

Evidence in the code;

vendor/solarium/solarium/library/Solarium/Core/Client/Client.php

    /**
     * Default options
     * 
     * @var array
     */
    protected $options = array(
        'adapter' => 'Solarium\Core\Client\Adapter\Curl',
        'endpoint' => array(
            'localhost' => array()
        )
    );

vendor/solarium/solarium/library/Solarium/Core/Client/Endpoint.php

    /**
     * Default options
     *
     * The defaults match a standard Solr example instance as distributed by
     * the Apache Lucene Solr project.
     *
     * @var array
     */
    protected $options = array(
        'scheme'  => 'http',
        'host'    => '127.0.0.1',
        'port'    => 8983,
        'path'    => '/solr',
        'core'    => null,
        'timeout' => 5,
    );

The endpoint check;

vendor/solarium/solarium/library/Solarium/Core/Client/Client.php

if (array_key_exists($key, $this->endpoints) && $this->endpoints[$key] !== $endpoint) {
  throw new InvalidArgumentException('An endpoint must have a unique key');
}

Not quite sure what the solution should be?.. I mean, we could trap someone trying to enter 'localhost' as their endpoint machine name and tell them that they can't but it'd be confusing as the list of servers would be blank.