MergeLeads fails - no way to specify required leadID

[JBCSU]

MarketoClient\LeadDatabase\Leads\MergeLeads specifies that leadId is a required property, but does not provide a leadId method to set the property. When called as follows, it fails with PHP Fatal error: Uncaught InvalidArgumentException: Required parameter leadId is missing.

$request = $this->marketo->leadDatabase()->mergeLeads()
    ->leadIds( $ids )
    ->mergeInCRM( $mergeInCRM );