Workbench attempts to get the relationship base type although repository does not support that object type

Workbench's login calls getType("cmis:relationship") regardless if repository supports relationships. An alternative is to get that object type only if getTypeChildren returns cmis:relationship in the list of base types. The spec says "The support for relationship objects is optional. The getTypeChildren service when asked for the base object-types MUST return the base relationship object-type if the repository supports relationships."