fix: missing idempotency key should not persist any data

[jeromevdl]

Issue #, if available: #1200

Description of changes:

Checking for null idempotency key, logging a warning and avoid persisting the record

Checklist

• Meet tenets criteria
• Update tests
• Update docs
• PR title follows conventional commit semantics

Breaking change checklist

RFC issue #:

• Migration process documented
• Implement warnings (if it can live side by side)

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[codecov-commenter]

Codecov Report

Patch coverage: 66.66% and project coverage change: -0.23 ⚠️

Comparison is base (c96c0ad) 71.20% compared to head (b4bdc91) 70.98%.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #1201      +/-   ##
============================================
- Coverage     71.20%   70.98%   -0.23%     
  Complexity      535      535              
============================================
  Files            71       71              
  Lines          2240     2254      +14     
  Branches        240      245       +5     
============================================
+ Hits           1595     1600       +5     
- Misses          532      540       +8     
- Partials        113      114       +1     

Impacted Files	Coverage Δ
...tools/idempotency/internal/IdempotencyHandler.java	66.12% <50.00%> (-1.09%)	⬇️
.../idempotency/persistence/BasePersistenceStore.java	84.33% <68.42%> (-3.90%)	⬇️

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[scottgerring]

LGTM