* MALFORMED_PARAMETER_ERROR - when type of the request parameter is invalid (String instead of Long for id for example)
* PARAM_ERROR - when invalid parameter value is specified in api request. For example, id of non existing vm for StartVmCmd
* ACCOUNT_RESOURCE_LIMIT_ERROR - when user tries to exceed his resource limits by executing the api command.
* INSUFFICIENT_CAPACITY_ERROR - when resource fails to create/start due to insufficient capacity.
* RESOURCE_UNAVAILABLE_ERROR - when user tries to create a vm when storage is not available.
* RESOURCE_IN_USE_ERROR - when user tries to delete/modify resource while it's in use. For example, when we try to delete a network group when it contains ingress rules.
* NETWORK_RULE_CONFLICT_ERROR - when LB/PF rule to add conflicts with existing rule
* ACCOUNT_ERROR - when user is not authorized to execute operation on the resource.
* INTERNAL_ERROR
2) Introduced responseObject field in @Implementation for all apis. This field contains information about the response object class, so we can used it for generating API documentation.
* Implement callCreate() and execute() methods in apis extending BaseAsyncCreateCmd (example - CreateVolumeCmd)
* Implement execute() method in apis extending BaseCmd and BaseAsyncCmd (example - deleteVolumeCmd and deleteUserCmd)
We no longer need createMethod(), method(), manager() fields in @Implementation annotation, cleanup has to be done.
2) Moved Account/User related methods to AccountManagerImpl. Methods are exposed via AccountService interface.
3) Enhanced exception handing for Api calls.
4) Created ConfigurationService interface, all Api config methods are exposed via it.