Backport: Fix NullPointerException when fetching findings

[nscuro]

Description

Fixes NullPointerException when fetching findings.

Addressed Issue

Fixes #4351 Backports https://github.com/DependencyTrack/dependency-track/pull/4369

Additional Details

N/A

Checklist

• [x] I have read and understand the contributing guidelines
• [x] This PR fixes a defect, and I have provided tests to verify that the fix is effective
• ~This PR implements an enhancement, and I have provided tests to verify that it works as intended~
• ~This PR introduces changes to the database model, and I have added corresponding update logic~
• ~This PR introduces new or alters existing behavior, and I have updated the documentation accordingly~

[codacy-production[bot]]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
Report missing for 25a252416aa552e351f4037bc730a96d7e07b8a3[^1]	:white_check_mark: 100.00% (target: 70.00%)

Coverage variation details

| | Coverable lines | Covered lines | Coverage | | ------------- | ------------- | ------------- | ------------- | | Common ancestor commit (25a252416aa552e351f4037bc730a96d7e07b8a3) | Report Missing | Report Missing | Report Missing | | | Head commit (c4559e1fbaccadbca4846460e2498ef9204155f8) | 22568 | 17858 | 79.13% | **Coverage variation** is the difference between the coverage for the head and common ancestor commits of the pull request branch: ` - `

Diff coverage details

| | Coverable lines | Covered lines | Diff coverage | | ------------- | ------------- | ------------- | ------------- | | Pull request (#4380) | 4 | 4 | **100.00%** | **Diff coverage** is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: `/ * 100%`

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_{Codacy stopped sending the deprecated coverage status on June 5th, 2024. Learn more} [^1]: Codacy didn't receive coverage data for the commit, or there was an error processing the received data. Check your integration for errors and validate that your coverage setup is correct.