How to get specific group of projects via list of key?

[Deleted user]

Hi, 

I am creating now dashboard plugin to replace old "Projects" gadget. 

I have now list of keys, but a few problems too:

* (Javascript + jQuery) If I get list of all projects via API, I can use simple loop for search all... but It can be overkill for browser (100+ projects).

* (Javascript + jQuery) I can create loop with query to API ("/project/{key}"), but It can be overkill for REST.

* (Java) Create a new endpoint where I send keys and get list of projects in JSON object.

Last point is the best in my opinion (say If I am wrong), but I don't have enough knowledge about Atlassian Java codes. 

Do you have source codes for create simple endpoints to do that? I saw "Developing a REST service plugin", but there is more questions than answers.