[lqiu96]

Summary

Reduces intermediate allocations and collection resizing in InsertAllRequest, BigQueryImpl.insertAll, and InsertAllResponse without changing lazy BigQueryError behavior:

• Flat ArrayList staging (InsertAllRequest.Builder.setRows): Stages rows in an ArrayList instead of a LinkedList (which allocates an internal Node object per row before build() copies them into an ImmutableList).
• Pre-sized insertAll loop (BigQueryImpl.insertAll): Replaces FluentIterable.from(rows).transform(...).toList() and its boolean[] wrapper with a plain for loop into new ArrayList<>(rows.size()). Because .toList() already materialized everything immediately while hiding .size(), pre-sizing avoids repeated array resizing on large batches.
• Pre-sized InsertAllResponse builders (InsertAllResponse.toPb / fromPb): Replaces ImmutableList.copyOf(Iterables.transform(...)) in toPb() with ImmutableList.builderWithExpectedSize(insertErrors.size()), and builds the ImmutableMap directly via ImmutableMap.builderWithExpectedSize(errorsPb.size()).buildKeepingLast() in fromPb() instead of copying through a temporary HashMap, while keeping Lists.transform on each row's BigQueryError list.

Verification

• mvn test -pl java-bigquery/google-cloud-bigquery -Dtest=InsertAllRequestTest,BigQueryImplTest -Dclirr.skip=true -Denforcer.skip=true -Dflatten.skip=true (InsertAllRequestTest: 21 passed, BigQueryImplTest: 133 passed)
• mvn test -pl java-bigquery/google-cloud-bigquery -Dtest=InsertAllResponseTest -Dclirr.skip=true -Denforcer.skip=true -Dflatten.skip=true (4 passed)

[gemini-code-assist]

Code Review

This pull request introduces several performance and memory optimizations across the BigQuery client library. Key improvements include replacing lazy Guava transformations with eager materialization using pre-sized collections, converting a LinkedList to an ArrayList in InsertAllRequest to reduce per-row memory overhead, and simplifying a mutable single-element boolean array to a standard boolean variable in BigQueryImpl. I have no feedback to provide as there are no review comments.