Returns a collection with the allowed actions based on the current stage as defined
in the SessionData. Possible actions are: prev, next and complete.
This method will never be invoked for commands that have no stages.
Returns the default label used for describing this commmand. This information is usually
used when returning commands as disco#items. Admins can later use AdHocCommand.setLabel(String)
to set a new label and reset to the default value at any time.
Returns which of the actions available for the current stage is considered the equivalent
to "execute". When the requester sends his reply, if no action was defined in the command
then the action will be assumed "execute" thus assuming the action returned by this
method. This method will never be invoked for commands that have no stages.
Returns the max number of stages for this command. The number of stages may vary according
to the collected data in previous stages. Therefore, a SessionData object is passed as a
parameter. When the max number of stages has been reached then the command is ready to