Created attachment 1183853 [details]
engine + server logs

Description of problem:
During our automation testing all the hosts in the cluster were non-operational or in maintenance.
When an attempt was done to create a vm pool, it failed but with an error which is too general and doesn't reflect the actual reason:

Status: 500
Reason: Internal Server Error
Detail: java.lang.NullPointerException

In engine log there's a long trance that starts with:

2016-07-23 16:07:35,070 ERROR [org.ovirt.engine.core.bll.CommandsFactory] (default task-7) [vmpools_create_aa8f40ab-39a8-4a49] An exception has occured while trying to create a command object for command 'AddVmPoolWithVms': WELD-000049: U
nable to invoke protected final void org.ovirt.engine.core.bll.CommandBase.postConstruct() on org.ovirt.engine.core.bll.AddVmPoolWithVmsCommand@3b7aa1f9
2016-07-23 16:07:35,110 ERROR [org.ovirt.engine.api.restapi.resource.AbstractBackendResource] (default task-7) [] Operation Failed: java.lang.NullPointerException
2016-07-23 16:07:35,110 ERROR [org.ovirt.engine.api.restapi.resource.AbstractBackendResource] (default task-7) [] Exception: javax.ejb.EJBException: java.lang.NullPointerException

Re produced this later also when all the hosts are on maintenance in another env.

Version-Release number of selected component (if applicable):
rhevm-4.0.2-0.2.rc1.el7ev.noarch

How reproducible:
alwyas

Steps to Reproduce:
1. Put all hosts in maintenance in a certain cluster.
2. Attempt to add a vm pool via API (v4)


Actual results:

Status: 500
Reason: Internal Server Error
Detail: java.lang.NullPointerException

Expected results:
The actual reason for the error: "Storage domain is not in state up, no hosts available in cluster" or the actual error message that already exists in these cases for e.g. attempting to create a vm in these conditions.

Additional info: