Grouping cache when loading data using CacheStore

[Ferry Syafei Sapei]

I have a CSV file with the following structure:

accountNumber,accountProperty1,accountProperty2,billNumber,billProperty1,billProperty2
100,property11,property12,100700,billProperty11,billProperty12
100,property11,property12,100700,billProperty21,billProperty22

I would like to import the file and fill in the cache with the following object 
structure:
class AccountInformation
        int accountNumber
        String accountProperty1
        String accountProperty2
        List<Bill> bills

class Bill
        int billNumber
        String billProperty1
        String billProperty2

I have tried using IgniteDataStreamer and StreamVisitor. Line by line will be 
read and added to the data stream. In the data streamer, I could check if the 
account information exists or not. If it exists, I just add the new bill to the 
existing account and replace the cache content for that account.

How can I achieve the same result using CacheStore?