Implement xls writer

implement a xls writer with apache poi

Deliveries?
- in our on premise git (access will be granted to you)
- full sources
- open source libs (need prior confirm)
- maven
- JDK 17
- code passes integrated PMD, findbugs and checkstyle checks

Payment?
- you estimate in a WBS after getting the task
- we discuss about clearances and effort
- we mutually agree to effort
- we assign you the task after agree
- you implement & delivery
- we pay
(basically the rules of freelancer)

Closed book vs open book?
We work only on open book.
Closed book means you are unwilling to define a WBS for the work and you add only a price tag to the task. We are sorry we will not hire you in such a case!