Whats the most elegant way to add two numbers that are Optional

Question

I need to perform an add operation on two big decimals that are wrapped optionals:

Optional ordersTotal;
Optional newOrder;
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Answer 1

What is wrong is your requirement not your solution. An empty Optional is not zero but a missing value. You're basically asking that 5 + NaN is equal to 5. Optional's flatMap guides you to the happy path: 5 + Nan is Nan and this is exactly what flatMap does.