[ahmedabu98]

Use RecordWriterManager to write through the HASH distribution mode. RecordWriterManager determines a destination file's partition from its rows instead of an incoming partition path. Using the parsed partition path directly resulted in some errors:

• year partitions stored the calendar year instead of years since 1970 (2024 instead of 54).
• Strings with spaces or special characters stayed URL-encoded (a b/c became a+b%2Fc).
• A null string became the string "null", so it shared a partition with real "null" values.
• A null boolean became false.
• Binary values became the bytes of their base64 text.
• Nulls in numeric and date partitions, including year, month, day and hour partitions, crashed the write.
• Identity partitions on timestamp or time columns crashed the write.

Added tests to make sure these are covered against future changes.

RecordWriterManager now numbers files per partition path, so a null and the string “null” no longer write the same file.
Also fixed Timestamp.MICROS, which used to crash.

[github-actions]

Assigning reviewers:

R: @chamikaramj for label iceberg.
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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 58.25%. Comparing base (acca614) to head (4e4fd8c).
⚠️ Report is 120 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##             master   #41012   +/-   ##
=========================================
  Coverage     58.25%   58.25%           
  Complexity     2277     2277           
=========================================
  Files          1136     1136           
  Lines        169341   169341           
  Branches       1482     1482           
=========================================
  Hits          98647    98647           
  Misses        68146    68146           
  Partials       2548     2548           

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[github-actions]

Reminder, please take a look at this pr: @chamikaramj