add some examples for functional programming in JAVA

[dev-abir]

This repository is missing some examples for functional programming in JAVA, we should add that. (I can too)

[dubesar]

@dev-abir great. Can you commit something for this?

[dev-abir]

yeah sure

[DeepanshuGOYAL05]

Can I add in this? and can you provide guidelines for Pull Request?

[kunal299]

@DeepanshuGOYAL05 You can add. Check out the guidelines:-
https://github.com/dubesar/Java-A-Z/blob/master/CONTRIBUTING.md