SOLR-17600 (Part 3/4): Migrate SolrJ and Utilities from MapSerializable

[isaric]

This is Part 3 of 4 to deprecate and remove the MapSerializable interface as part of SOLR-17600.

This PR migrates SolrJ classes, test utilities, and stream explanations to use MapWriter.

Note: This PR is part of a stacked series and is built on top of Part 1 (#4463) and Part 2 (#4464). It currently displays the commits from Parts 1 & 2 as well, but they will automatically drop from this PR's diff once the previous parts are merged into main.

[Copilot]

Pull request overview

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This PR migrates a large set of Solr components from the legacy MapSerializable#toMap(...) pattern to the newer MapWriter#writeMap(...) model, often using SimpleOrderedMap / Utils.convertToMap(...) for materialization where a concrete map is required.

Changes:

• Convert multiple production classes and DTOs from MapSerializable to MapWriter and replace toMap(...) implementations with writeMap(...).
• Replace many toMap(new LinkedHashMap<>()) call sites with new SimpleOrderedMap<>(...) or Utils.convertToMap(...).
• Remove some MapSerializable-based serialization branches in writers/codecs and modernize a few helper conversions.

Reviewed changes

Copilot reviewed 49 out of 49 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
solr/test-framework/src/java/org/apache/solr/common/cloud/ClusterStateUtil.java	Switch debug state mapping to SimpleOrderedMap materialization.
solr/solrj/src/test/org/apache/solr/client/solrj/SolrExampleCborTest.java	Use SimpleOrderedMap when converting docs for CBOR test payloads.
solr/solrj/src/java/org/apache/solr/common/util/Utils.java	Adjust deep-copy and reflection mapping to rely on MapWriter + conversion helpers.
solr/solrj/src/java/org/apache/solr/common/util/TextWriter.java	Remove MapSerializable special-casing during text serialization.
solr/solrj/src/java/org/apache/solr/common/util/JavaBinCodec.java	Remove MapSerializable special-casing during javabin serialization.
solr/solrj/src/java/org/apache/solr/common/cloud/ZkNodeProps.java	Materialize MapWriter props via SimpleOrderedMap.
solr/solrj/src/java/org/apache/solr/common/MapWriterMap.java	Drop toMap(...) override now that MapWriter no longer extends MapSerializable.
solr/solrj/src/java/org/apache/solr/common/MapWriter.java	Remove MapSerializable inheritance and modernize EntryWriter#getBiConsumer.
solr/solrj/src/java/org/apache/solr/common/IteratorWriter.java	Convert nested MapWriter elements using SimpleOrderedMap.
solr/solrj-streaming/src/java/org/apache/solr/client/solrj/io/stream/expr/StreamExplanation.java	Convert from toMap(...) to writeMap(...) implementation (child handling changed).
solr/solrj-streaming/src/java/org/apache/solr/client/solrj/io/stream/expr/Explanation.java	Convert Explanation to implement MapWriter and emit fields via EntryWriter.
solr/modules/extraction/src/java/org/apache/solr/handler/extraction/TikaServerExtractionBackend.java	Copy init-args into a map via SimpleOrderedMap.
solr/core/src/test/org/apache/solr/update/SolrIndexConfigTest.java	Update tests to expect MapWriter and use SimpleOrderedMap for mapping.
solr/core/src/test/org/apache/solr/handler/designer/TestSchemaDesignerAPI.java	Convert params mapping to use SimpleOrderedMap.
solr/core/src/test/org/apache/solr/core/TestConfig.java	Update test mapping to SimpleOrderedMap.
solr/core/src/test/org/apache/solr/core/CacheConfigTest.java	Update cache config mapping in tests to SimpleOrderedMap.
solr/core/src/test/org/apache/solr/api/NodeConfigClusterPluginsSourceTest.java	Convert config mapping from toMap(...) into SimpleOrderedMap.
solr/core/src/java/org/apache/solr/update/SolrIndexConfig.java	Convert SolrIndexConfig to MapWriter and implement writeMap(...).
solr/core/src/java/org/apache/solr/update/IndexFingerprint.java	Convert to MapWriter and update toString() materialization.
solr/core/src/java/org/apache/solr/search/CacheConfig.java	Convert to MapWriter and emit args via a NamedList writer.
solr/core/src/java/org/apache/solr/schema/IndexSchema.java	Convert SchemaProps to MapWriter and return values via SimpleOrderedMap.
solr/core/src/java/org/apache/solr/handler/export/ExportWriterStream.java	Convert nested MapWriter values to SimpleOrderedMap when building tuples.
solr/core/src/java/org/apache/solr/handler/designer/ManagedSchemaDiff.java	Use Utils.convertToMap for diffing SimpleOrderedMap instances.
solr/core/src/java/org/apache/solr/handler/admin/api/SplitShardAPI.java	Use Utils.convertToMap for v2 payload → v1 params conversion.
solr/core/src/java/org/apache/solr/handler/admin/api/SplitCoreAPI.java	Use Utils.convertToMap for v2 payload → v1 params conversion.
solr/core/src/java/org/apache/solr/handler/admin/api/RequestSyncShardAPI.java	Use Utils.convertToMap for v2 payload → v1 params conversion.
solr/core/src/java/org/apache/solr/handler/admin/api/RequestCoreRecoveryAPI.java	Use Utils.convertToMap for v2 payload → v1 params conversion.
solr/core/src/java/org/apache/solr/handler/admin/api/RequestBufferUpdatesAPI.java	Use Utils.convertToMap for v2 payload → v1 params conversion.
solr/core/src/java/org/apache/solr/handler/admin/api/RequestApplyCoreUpdatesAPI.java	Use Utils.convertToMap for v2 payload → v1 params conversion.
solr/core/src/java/org/apache/solr/handler/admin/api/RejoinLeaderElectionAPI.java	Use Utils.convertToMap for v2 payload → v1 params conversion.
solr/core/src/java/org/apache/solr/handler/admin/api/RebalanceLeadersAPI.java	Use Utils.convertToMap for v2 payload → v1 params conversion.
solr/core/src/java/org/apache/solr/handler/admin/api/PrepareCoreRecoveryAPI.java	Use Utils.convertToMap for v2 payload → v1 params conversion.
solr/core/src/java/org/apache/solr/handler/admin/api/OverseerOperationAPI.java	Use SimpleOrderedMap for payload → params conversion.
solr/core/src/java/org/apache/solr/handler/admin/api/MoveReplicaAPI.java	Use Utils.convertToMap for v2 payload → v1 params conversion.
solr/core/src/java/org/apache/solr/handler/admin/api/ModifyCollectionAPI.java	Use Utils.convertToMap for v2 payload → v1 params conversion.
solr/core/src/java/org/apache/solr/handler/admin/api/MigrateDocsAPI.java	Use Utils.convertToMap for v2 payload → v1 params conversion.
solr/core/src/java/org/apache/solr/handler/admin/api/InstallShardData.java	Use Utils.convertToMap before creating ZkNodeProps.
solr/core/src/java/org/apache/solr/handler/admin/api/CreateCore.java	Use Utils.convertToMap for v1 SolrParams → request-body conversion.
solr/core/src/java/org/apache/solr/handler/admin/ZookeeperInfoHandler.java	Use Utils.convertToMap when materializing DocCollection.
solr/core/src/java/org/apache/solr/handler/admin/IndexSizeEstimator.java	Replace ad-hoc map creation with SimpleOrderedMap materialization.
solr/core/src/java/org/apache/solr/handler/admin/BaseHandlerApiSupport.java	Switch request parameter export from toMap(...) to writeMap(...).
solr/core/src/java/org/apache/solr/handler/SolrConfigHandler.java	Update config/plugin info materialization to MapWriter + SimpleOrderedMap.
solr/core/src/java/org/apache/solr/handler/ClusterAPI.java	Use SimpleOrderedMap when converting RoleInfo to params.
solr/core/src/java/org/apache/solr/filestore/ClusterFileStore.java	Copy metadata into response properties via SimpleOrderedMap.
solr/core/src/java/org/apache/solr/core/SolrConfig.java	Convert core config mapping to MapWriter and restructure emitted maps via SimpleOrderedMap.
solr/core/src/java/org/apache/solr/core/RequestParams.java	Convert RequestParams/ParamSet to MapWriter and adjust map materialization call sites.
solr/core/src/java/org/apache/solr/core/PluginInfo.java	Convert PluginInfo to MapWriter and update serialization logic.
solr/core/src/java/org/apache/solr/core/ConfigOverlay.java	Convert overlay mapping to MapWriter.
solr/core/src/java/org/apache/solr/api/NodeConfigClusterPluginsSource.java	Simplify initArgs config mapping using NamedList#asMap.

Comments suppressed due to low confidence (3)

solr/solrj-streaming/src/java/org/apache/solr/client/solrj/io/stream/expr/StreamExplanation.java:1

• This no longer emits a children field at all. Previously children was a list under the key \"children\"; now each child is written into the same map as the parent, which both changes the JSON shape and risks key collisions/overwrites. Restore the children list structure by collecting children into a list value (or emitting an array writer) and putting it once under \"children\".
  solr/solrj/src/java/org/apache/solr/common/util/TextWriter.java:1
• This removes the MapSerializable serialization path entirely. If any objects still implement MapSerializable but not MapWriter (or are provided by external plugins), they will now fall through and may be rendered incorrectly or fail to serialize. If MapSerializable is still supported/used, reintroduce a compatibility branch (or provide a bridging adapter to MapWriter) until all MapSerializable producers are fully migrated.
  solr/test-framework/src/java/org/apache/solr/common/cloud/ClusterStateUtil.java:1
• The comment claims JSON conversion requires "standard types like Map", but the code now stores a SimpleOrderedMap as the value. If SimpleOrderedMap is intentionally acceptable for Utils.toJSONString(...) (and/or is treated as a Map-like type by the JSON layer), the comment should be updated to avoid misleading future readers; otherwise, consider materializing to an actual Map to match the comment.

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