Automated SDK update

This updates the SDK from internal repo commit segmentio/public-api@b48cd468.

Author: APIs and Common Services team

src/main/java/com/segment/publicapi/models/AudienceOptions.java

@@ -89,7 +89,9 @@ public AudienceOptions addFilterByExternalIdsItem(String filterByExternalIdsItem
     /**
      * The set of profile external identifiers being used to determine audience membership. Profiles
      * will only be considered for audience membership if the profile has at least one external id
-     * whose key matches a value in this set.
+     * whose key matches a value in this set. If unspecified, a default set of external identifiers
+     * will be used: ['user_id', 'email', 'android.idfa',
+     * 'ios.idfa'].
      *
      * @return filterByExternalIds
      */