The CDAP CLI is a command-line interface for CDAP.
Adding a new command can be done by adding your command to DefaultCommands.
You can either add a single command by adding an instance of it to the first constructor argument
or by adding an instance of the command to one of the CommandSet in the second constructor argument.
Associating a completer with an ArgumentName can be done by registering your ArgumentName and completer
in DefaultCompleters. Once your ArgumentName is associated with your completer, the CLI will autocomplete
your ArgumentName in command patterns for the users.
For example, if you register an ArgumentName named "app-jar-file" with a FileNameCompleter, and
you have a command that has the pattern deploy app <app-jar-file>, then the CLI will use the FileNameCompleter
to autocomplete when the user requests autocompletion for <app-jar-file>.