Improve array validator to also check for blank string in addition to null

[cwperks]

Description

Improve array validator to also check for blank string in addition to null

• Category (Enhancement, New feature, Bug fix, Test fix, Refactoring, Maintenance, Documentation)

Bug fix

Check List

• New functionality includes testing
• New functionality has been documented
• New Roles/Permissions have a corresponding security dashboards plugin PR
• API changes companion pull request created
• Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
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[codecov]

Codecov Report

❌ Patch coverage is 75.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 72.89%. Comparing base (7d5b506) to head (7808832).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
.../dlic/rest/validation/RequestContentValidator.java	75.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5714      +/-   ##
==========================================
- Coverage   72.91%   72.89%   -0.02%     
==========================================
  Files         412      412              
  Lines       26207    26207              
  Branches     3964     3964              
==========================================
- Hits        19108    19103       -5     
- Misses       5193     5196       +3     
- Partials     1906     1908       +2     

Files with missing lines	Coverage Δ
.../dlic/rest/validation/RequestContentValidator.java	89.71% <75.00%> (ø)

... and 7 files with indirect coverage changes

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