Add a SortedMap data structure

[the-c0d3br34k3r]

• [ ] Description A clear and concise description of request/enhancement.
  
• [ ] Use cases
  1. Datastructures.
• [ ] Proposed design A clear and concise description of the design planned for this feature/enhancement. Attach design diagrams if applicable.
• [ ] Alternative design approaches A list of other approaches that could've been taken to design this feature/enhancement, but hasn't been because of a specified reason.
• [ ] Workaround If any workaround exists to achieve the desired goal without this feature/enhancement.
• [ ] Additional information Add any other context about the problem here.

[the-c0d3br34k3r]

Closing issue as SortedMap is available in Java - https://docs.oracle.com/javase/9/docs/api/java/util/SortedMap.html?is-external=true.