Write a RESTful service that calculates prime numbers.
Try and implement more than 1 algorithm Try and use multiple threads. It must be written Java 8. You can use your favourite open source libraries and frameworks e.g. drop wizard, spring. You must use maven. You must have unit tests. The project must be available from a GitHub account.
I am looking for good design, use of appropriate libraries and attention to detail, especially around unhappy paths.