Avoid illegal-mutation error

[atognolag]

Small fix to prevent illegal mutations of input elements by the .get() method of the ByteBuffer object.

Please refer to [Bug]: Illegal mutation in kafka-to-bigquery #2036 for more information

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 45.50%. Comparing base (94a7e9f) to head (30688cb).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
...gle/cloud/teleport/v2/utils/BigQueryAvroUtils.java	0.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #2037      +/-   ##
============================================
+ Coverage     45.42%   45.50%   +0.08%     
- Complexity     3678     4026     +348     
============================================
  Files           842      845       +3     
  Lines         49970    50083     +113     
  Branches       5261     5267       +6     
============================================
+ Hits          22697    22792      +95     
- Misses        25605    25619      +14     
- Partials       1668     1672       +4     

Components	Coverage Δ
spanner-templates	66.90% <ø> (+0.17%)	⬆️
spanner-import-export	64.18% <ø> (-0.05%)	⬇️
spanner-live-forward-migration	75.88% <ø> (ø)
spanner-live-reverse-replication	76.65% <ø> (ø)
spanner-bulk-migration	86.55% <ø> (+0.17%)	⬆️

Files with missing lines	Coverage Δ
...gle/cloud/teleport/v2/utils/BigQueryAvroUtils.java	0.00% <0.00%> (ø)

... and 8 files with indirect coverage changes