Hi Rajendran,
Is there a specific functionality for which you need the UML Class diagram?
Below is the link to our latest product documentation, hope that will be suffice for now.
https://documentation.nexj.com/crmdev93/application-services/relationship-management-services
If you need more detailed diagrams we can provide support to build a new one in NexJ studio with you, since the application has many features there is no “one” diagram for everything.