Customers are containers for users. In a B2C scenario exactly one user is assigned
to a customer. In a B2B scenario at least one user is assigned to the customer.
Besides the users a customer has an ID, a localizable name and a customer type.
References assigned users.
Cost object types describe what kind of object the cost object represents.
For example Project Number, Contract Number, Cost Center, etc.
They should have unique name attribute(per customer) and optional translations for display name and description.
Generic type for XML element which contains text translation in language specified by xml:lang attribute