The Client Backpressure specification expands the driver's overload retry policy to all commands, including those that are not eligible for retry under the read/write retry policies.

Today, a set of write-command operations dispatch their server command with no retry wrapper at all, so a server SystemOverloadedError on these commands is surfaced immediately instead of being retried with backoff.

The authoritative list of affected commands comes from:

• retryable-writes spec — Unsupported Write Operations: write commands other than insert / update / delete / findAndModify, e.g. aggregate with $out / $merge.
• retryable-reads spec — Unsupported Read Operations.

Peer drivers have already implemented this:

• PyMongo retries all of these gated on retry_writes (including the search-index ops).
• Node retries all except the search-index ops.

Scope

Add overload-only retry, composed via

SpecRetryPolicy.IndividualPolicies(retryWrites)
        .includeOverload(maxAdaptiveRetries, AS_WRITE_POLICY)

to the following operations, gated on the client retryWrites setting:

• createIndexes
• dropIndexes
• createCollection
• createView
• dropCollection
• dropDatabase
• renameCollection
• aggregate with $out / $merge
• createSearchIndexes, updateSearchIndex, dropSearchIndex

Overload-only (not includeWrite()) because these commands are ineligible for write retry - no txnNumber / retryable-writes semantics should be added.

Non-goals

• mapReduce (inline and to-collection) — deprecated in the driver, removed from MongoDB 5.0 and PyMongo; excluded.
• Unacknowledged w:0 writes - no response carries an overload error.
• runCommand (JAVA-6294), getMore (JAVA-6296), multi-doc update / delete - already overload-retried.
• killCursors overload retry - tracked separately.

Acceptance criteria 

1. All affected operations overload-retry up to maxAdaptiveRetries times when the server returns SystemOverloadedError + RetryableError, gated on retryWrites.
2. No retry when retryWrites=false or on non-overload errors.
3. The 8 previously JAVA-5956-skipped unified client-backpressure scenarios (createIndex / dropIndex / dropIndexes / aggregate-write) pass for both sync and reactive drivers.
4. Prose tests cover the operations that lack unified coverage (admin / index / search-index commands).