It is fine to have just one class, until it maps all the persistent classes.
The OpenAccess enhancer looks up for all inheritors of the FluentMetadataSource class in the assembly, currently being enhanced, initializes them and then goes through them in order to get the collections of mappings. Using the FluentMetadataSource Class
article gets into details on this.
the Telerik team
Explore the entire Telerik portfolio by downloading the Ultimate Collection trial package. Get now >>