Fix NPE on findHostsForMigration when no suitable hosts are found

[winterhazel]

Description

This patch fixes a NPE findHostsForMigration introduced in #9074 that occurs when no suitable hosts are found (suitableHosts is null) due to a missing return statement.

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)
• Build/CI
• Test (unit or integration test code)

Feature/Enhancement Scale or Bug Severity

Bug Severity

• BLOCKER
• Critical
• Major
• Minor
• Trivial

How Has This Been Tested?

In a test environment with two hosts, host-1 and host-2:

1. I deployed a VM in host-1.
2. I disabled host-2.
3. I attempted to open the VM migration wizard.

Before the patch, I would get a NPE in step 3. Now, I do not receive the NPE anymore.

[winterhazel]

@blueorangutan package

[blueorangutan]

@winterhazel a [SL] Jenkins job has been kicked to build packages. It will be bundled with no SystemVM templates. I'll keep you posted as I make progress.

[codecov]

Codecov Report

❌ Patch coverage is 20.00000% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 18.09%. Comparing base (72b99a3) to head (bf3addd).

Files with missing lines	Patch %	Lines
...in/java/com/cloud/server/ManagementServerImpl.java	20.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##               main   #13138   +/-   ##
=========================================
  Coverage     18.08%   18.09%           
- Complexity    16718    16722    +4     
=========================================
  Files          6037     6037           
  Lines        542546   542546           
  Branches      66432    66431    -1     
=========================================
+ Hits          98146    98165   +19     
+ Misses       433378   433358   -20     
- Partials      11022    11023    +1     

Flag	Coverage Δ
uitests	3.51% <ø> (ø)
unittests	19.25% <20.00%> (+<0.01%)	⬆️

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[sureshanaparti]

clgtm

[blueorangutan]

Packaging result [SF]: ✔️ el8 ✔️ el9 ✔️ el10 ✔️ debian ✔️ suse15. SL-JID 17786