Fix npe when migrating vm with volume

[GutoVeronezi]

Description

In the execution flow of the API migrateVirtualMachineWithVolume, there is a step that copies the volume's template to the target storage, if it is needed.
In some cases when the volume is a data type, it (the volume) does not have a template; therefore, it is going to generate an NPE when it tries to get the template's ID (Long to long auto conversion).

This PR intends to validate if the volume being copied has a template, before trying to copy the template.

Types of changes

• Breaking change (fix or feature that would cause existing functionality to change)
• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Enhancement (improves an existing feature and functionality)
• Cleanup (Code refactoring and cleanup, that may add test cases)

Feature/Enhancement Scale or Bug Severity

Feature/Enhancement Scale

• Major
• Minor

Bug Severity

• BLOCKER
• Critical
• Major
• Minor
• Trivial

How Has This Been Tested?

It has been tested locally in a test lab.

1. I had created a VM and attached 2 volumes to it.
2. I had migrated the VM to another host and the volumes to different storage to see if it migrates accordingly.

[shwstppr]

@GutoVeronezi which hypervisor this NPE was seen because I didn't face it on VMware.
Also, since this is a bug fix it should go to 4.15.1

@blueorangutan package

[blueorangutan]

@shwstppr a Jenkins job has been kicked to build packages. I'll keep you posted as I make progress.

[blueorangutan]

Packaging result: ✔centos7 ✔centos8 ✔debian. JID-2728

[rafaelweingartner]

@abhinandanprateek this happens on KVM.

I would like to highlight one thing here. The contributor is willing to send the changes/patch to master. We (as the ACS community) can never force the contributor to do anything he/she does not want (and that is not a technical part of the contribution). We can review the code and ask for improvement/changes; we can try to convince the contributor to send the code to an already release version, but we can not say "it is a bug fix, so send it to x.y.z" (this sounds like an order). However, as the name says, it is a contribution. Therefore, it is non-paid work dedicated to ACS that somebody is providing (unless you somehow are providing this contribution by supporting the contributor). I have seen this happening in other PRs, and as a member of the PMC I would like to highlight that this is not part of the Apache Way.

If somebody/some company in the community liked the changes and would like to see it in a specific branch, they can cherry-pick/back-port from master to the version branch they want.

Please, it is nothing personal or anything. It is just something I noticed, and that we (as a community) should pay attention to.

[GabrielBrascher]

Code LGTM

[DaanHoogland]

clgtm. I also like the logging even though (in some of these cases) if(LOGGER.isDebugEnabled) would make the code more readible!

[Pearl1594]

Verified behavior. LGTM