Prevent NPE if guest OS mapping is missing while prioritizing hosts

[khos2ow]

Description

When starting an existing VM and trying to prioritize hosts, if Guest OS mapping has been removed from that host, there will be a NullPointerException which prevents the VM to be started successfully.

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)

GitHub Issue/PRs

Screenshots (if appropriate):

How Has This Been Tested?

Checklist:

• I have read the CONTRIBUTING document.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
  Testing
• I have added tests to cover my changes.
• All relevant new and existing integration tests have passed.
• A full integration testsuite with all test that can run on my environment has passed.

@blueorangutan package

[blueorangutan]

@khos2ow a Jenkins job has been kicked to build packages. I'll keep you posted as I make progress.

[rafaelweingartner]

if you return a null value in getTemplateGuestOSCategory method, why not simply check templateGuestOSCategory == null?

Is it possible to have an empty or blank guestOSCategory.name?
BTW: Strings.isNullOrEmpty will return false for blanks.

[khos2ow]

Technically templateGuestOSCategory == null would be enough, and I cannot think of a way getTemplateGuestOSCategory returning empty string unless the database record integrity has been changed, that's why I used Strings.isNullOrEmpty rather rather than a simple == null check. (which might be slightly overkill at the same time!)

[blueorangutan]

Packaging result: ✔centos6 ✔centos7 ✔debian. JID-1938

[yadvr]

@khos2ow can you change base branch to 4.11?

[khos2ow]

@rhtyd done.

[yadvr]

LGTM

[yadvr]

@blueorangutan package

[blueorangutan]

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

[blueorangutan]

Packaging result: ✔centos6 ✖centos7 ✖debian. JID-1952

[borisstoyanov]

LGTM

[DaanHoogland]

sorry for merging this. I did not check the integration tests. hope i will be forgiven one day.

[yadvr]

LGTM, given the changes on discretion I'm okay to accept/merge this as travis passed.