TD Software Developer interview questions

Apart from the homework assessment in which I was asked to merge 3 csv data files into a single report with certain rules (refdata and trade join by column Inventory, trade and valuation join by column TradeId, The output will be based on the Trade file. If no valuation or refdata for a given trade, then leave the "refdata" and "valuation" fields BLANK), I went into a three-round interview with some overlapping technical questions about concurrency, how to manage huge amounts of data in a REST request, main differences between java 8 (the language I used to do the assessment) and the most recent versions of the language.