Is it necessary for the Client to serialize and send back the same java object for Client-Server model where an object gets passed around?

Context: I send object Item between the client and server. For the server, I need the full Item with all its properties such as: price, components, name... (what I need). However, my only intent and need is to send back Item.components to the server. I find it difficult to construct the identical object in Javascript. Is it correct to respond with Item or String[] components ?