Description
See spec in parent issue (SPARK-18085) for more details.
This task tracks simplifying the REST API hierarchy. Because a lot of the code used for the current version of the REST API will be deleted as part of the UI work (see SPARK-20648, SPARK-20647, SPARK-20646, SPARK-20645), we can simplify the code by merging a bunch of the existing resource classes in the REST API (and also getting rid of some duplication in the process).