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).
⚠️ Report is 9 commits behind head on main.

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

[weizhouapache]

code lgtm

[weizhouapache]

@blueorangutan test

[blueorangutan]

@weizhouapache a [SL] Trillian-Jenkins test job (ol8 mgmt + kvm-ol8) has been kicked to run smoke tests

[weizhouapache]

verified OK

[blueorangutan]

[SF] Trillian test result (tid-16067)
Environment: kvm-ol8 (x2), zone: Advanced Networking with Mgmt server ol8
Total time taken: 75744 seconds
Marvin logs: https://github.com/blueorangutan/acs-prs/releases/download/trillian/pr13138-t16067-kvm-ol8.zip
Smoke tests completed. 146 look OK, 5 have errors, 0 did not run
Only failed and skipped tests results shown below:

Test	Result	Time (s)	Test File
test_vm_backup_create_vm_from_backup	Failure	607.85	test_backup_recovery_nas.py
test_vm_backup_lifecycle	Error	1.13	test_backup_recovery_nas.py
ContextSuite context=TestSharedFSLifecycle>:setup	Error	0.00	test_sharedfs_lifecycle.py
test_10_attachAndDetach_iso	Failure	607.23	test_vm_life_cycle.py
test_01_create_vm_snapshots	Failure	606.81	test_vm_snapshots.py
test_02_revert_vm_snapshots	Failure	600.75	test_vm_snapshots.py
test_03_delete_vm_snapshots	Failure	0.03	test_vm_snapshots.py
test_01_create_volume	Failure	612.42	test_volumes.py
test_01_root_volume_encryption	Failure	686.71	test_volumes.py
test_02_data_volume_encryption	Failure	639.83	test_volumes.py
test_03_root_and_data_volume_encryption	Failure	658.89	test_volumes.py
test_02_attach_volume	Failure	1266.26	test_volumes.py
test_02_attach_volume	Failure	1266.28	test_volumes.py
test_03_download_attached_volume	Failure	665.82	test_volumes.py
test_04_delete_attached_volume	Failure	663.70	test_volumes.py
test_05_detach_volume	Failure	751.70	test_volumes.py
test_06_download_detached_volume	Failure	845.17	test_volumes.py
test_07_resize_fail	Failure	657.54	test_volumes.py
test_08_resize_volume	Failure	660.99	test_volumes.py
test_09_delete_detached_volume	Failure	659.75	test_volumes.py
test_10_list_volumes	Failure	658.46	test_volumes.py
test_11_attach_volume_with_unstarted_vm	Failure	756.44	test_volumes.py
test_12_resize_volume_with_only_size_parameter	Failure	663.92	test_volumes.py
test_13_migrate_volume_and_change_offering	Failure	793.60	test_volumes.py
test_14_delete_volume_delete_protection	Failure	663.91	test_volumes.py

[weizhouapache]

merging, the test failures are unrelated