src/Services/ApplicationService.php
public function findKey($key, $postVars)
    {
        $multiselectKey = str_replace('[]', '', $key);
        if (array_key_exists($key, $postVars)) {
            return $key;
        } else if (array_key_exists($multiselectKey, $postVars)) {
            return $multiselectKey;
        } else {
            return null;
        }
    }
public function findKey($key, $postVars)
    {
        $multiselectKey = str_replace('[]', '', $key);
        if (array_key_exists($key, $postVars)) {
            return $key;
        } else if (array_key_exists($multiselectKey, $postVars)) {
            return $multiselectKey;
        } else {
            return null;
        }
    }
This fixes an issue where the Greenhouse API returns required multiselects as <field[]> but we require
the user to submit it as <field>, thus making the system think the required field is not set.  This
checks that either <field> or <field[]> is set, in order to work correctly but also be backward
compatable in case external systems have already corrected for it.

@params  Array   $key        The key to check for in $postVars
@params  Array   $postVars   Greenhouse post parameters.
@return  Mixed   string/null