Add JobModel and JobJSON a field that contains the name of the SDK used (that also contains the name of the programming language) and add the instructions to fetch this data in the JobModel Constructor.
Modify JobsServlet to store to DataStore this new data fetched.
Added aggregateByProgrammingLanguage to Agregation Center that group the jobs based on the language found and designed unit test for it
Make the code more modularized in AggregationCenter class (aggregate the jobs based on a key generated as needed) - added an interface (KeyGenerator) that deals with generating the key and use various implementations of this interface when calling aggregateBy