* Shared function can be put in the abstract class and this also enforces some interface methods
* Initialize a default dbFactory when it's not passed to the mapper
Change-Id: I1033dafaa90a1f683fbe9ad69bed04f4844e357b
* Get rid of EchoBackend by separating responsibilities into smaller objects
* Move main fetchNotification logic from API to a more appropriate place
* Add more unit testing coverage
Change-Id: I42f4d7566543332588431c21c220c0d64d026b70