[PR] [ISSUE #D13] Honor registerBroker's null-tolerant wrapper contract before its guards [rocketmq]

["zjncs (via GitHub)" <gi...@apache.org>]

zjncs opened a new pull request, #11120:
URL: https://github.com/apache/rocketmq/pull/11120

   ## Motivation
   
   `RouteInfoManager.registerBroker` is written to tolerate a partially-filled `TopicConfigSerializeWrapper`: later in the method the wrapper is null-checked (`if (null != topicConfigWrapper ...)`), its table is null-checked (`if (tcTable != null)`), and the `BrokerLiveInfo` construction falls back to `new DataVersion()` for a null wrapper. But two earlier dereferences run before those guards:
   
   ```java
   long newStateVersion = topicConfigWrapper.getDataVersion().getStateVersion();   // version-conflict check
   ...
   if (!brokerAddrsMap.containsKey(brokerId) && topicConfigWrapper.getTopicConfigTable().size() == 1) {  // single-topic rejection
   ```
   
   A wrapper decoded from a malformed register body can carry explicit `null` fields (JSON null), so:
   
   - The version-conflict check NPEs, the catch clause aborts the registration **after** `clusterAddrTable`/`brokerAddrTable` were already mutated — the broker is left partially registered until its next heartbeat.
   - A null `getDataVersion()` that reaches the `BrokerLiveInfo` construction is stored into `brokerLiveTable`, and every later address-change registration for that broker then NPEs at `oldBrokerInfo.getDataVersion().getStateVersion()`.
   
   ## Modification
   
   - Skip the version-conflict rejection when either side's `DataVersion` is unavailable.
   - Skip the single-topic rejection when the wrapper or its table is null.
   - Fall back to `new DataVersion()` in the `BrokerLiveInfo` construction when `getDataVersion()` is null, not only when the whole wrapper is null.
   
   ## Test Evidence
   
   **Fail-before** (unpatched code, new tests):
   
   ```
   docker exec rmq-build mvn -q -pl namesrv test -Dtest='RouteInfoManagerTest#testRegisterBrokerWithIncompleteWrapper' -Dsurefire.failIfNoSpecifiedTests=true
   ERROR RocketmqNamesrv - registerBroker Exception
   java.lang.NullPointerException: ... TopicConfigSerializeWrapper.getDataVersion()" is null
   Tests run: 1, Failures: 1 ... Expecting actual not to be null   // registration aborted, no live entry for the new address
   
   docker exec rmq-build mvn -q -pl namesrv test -Dtest='RouteInfoManagerTest#testRegisterBrokerWithNullWrapper' -Dsurefire.failIfNoSpecifiedTests=true
   Tests run: 1, Failures: 1 ... Expecting actual not to be null
   ```
   
   **Pass-after** (full class with the fix — both registrations complete):
   
   ```
   docker exec rmq-build mvn -q -pl namesrv test -Dtest='RouteInfoManagerTest' -Dsurefire.failIfNoSpecifiedTests=true
   Tests run: 14, Failures: 0, Errors: 0, Skipped: 0
   ```
   
   No associated issue (self-discovered during a namesrv-module self-audit).


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