Thanks Ronald for the prompt response, I will assure that we will discuss the project within the rule. Feel free to point me if I violate the rules.
I also have done something (class diagram, component diagram and sequence diagram) but got some confusion as following, please share your views.
1. How to show (class diagram/component diagram) that my design is extensible?
The BDOM is showing three classes (Brake Pad, Brake Discs, suspension) but we need to make the design extensible." with additional part types coming in later phases."
In my opinion, if there is one more part them there will be one more class added in the class diagram and there will one more master table (i.e. headlight master) in the database.
(Sorry I am thinking the implementation)
As per following comment to address extensibility but that violates the OO design,
you should have specialized classes for specialized part.
"Pratik Das: I have replaced the three parts with a single class part type but I have not used the enumeration. Using enumeration will entail changing the class model each time we add a new part type."
2. Why we need to initialize all the part type object, all we need is the part specification in the request object and quantity?
3. For the 1st use case, are we going to have multiple part types in single request o?
Then only we can justify 1-* relation between request and PO but if the request will have single item then it is in correct.