[GRPC][Joining queries] Implement GRPC Nested query, fix InnerHits, and bump to 0.19.0 protobufs

CHANGELOG.md

@@ -38,6 +38,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - [Search Stats] Add search & star-tree search query failure count metrics ([#19210](https://github.com/opensearch-project/OpenSearch/issues/19210))
 - [Star-tree] Support for multi-terms aggregation ([#18398](https://github.com/opensearch-project/OpenSearch/issues/18398))
 - Add stream search feature flag and auto fallback logic ([#19373](https://github.com/opensearch-project/OpenSearch/pull/19373))
+- Implement GRPC Exists, Regexp, and Wildcard queries ([#19392](https://github.com/opensearch-project/OpenSearch/pull/19392))
+- Implement GRPC GeoBoundingBox, GeoDistance queries ([#19451](https://github.com/opensearch-project/OpenSearch/pull/19451))
+- Implement GRPC Ids, Range, and Terms Set queries ([#19448](https://github.com/opensearch-project/OpenSearch/pull/19448))
+- Implement GRPC Nested query ([#19453](https://github.com/opensearch-project/OpenSearch/pull/19453))
 
 ### Changed
 - Refactor `if-else` chains to use `Java 17 pattern matching switch expressions`(([#18965](https://github.com/opensearch-project/OpenSearch/pull/18965))

modules/transport-grpc/src/main/java/org/opensearch/transport/grpc/proto/request/search/query/NestedQueryBuilderProtoConverter.java

@@ -0,0 +1,47 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.transport.grpc.proto.request.search.query;
+
+import org.opensearch.index.query.QueryBuilder;
+import org.opensearch.protobufs.QueryContainer;
+import org.opensearch.transport.grpc.spi.QueryBuilderProtoConverter;
+import org.opensearch.transport.grpc.spi.QueryBuilderProtoConverterRegistry;
+
+/**
+ * Converter for NestedQuery protobuf messages to OpenSearch QueryBuilder objects.
+ * Handles the conversion of nested query protobuf messages to OpenSearch NestedQueryBuilder.
+ */
+public class NestedQueryBuilderProtoConverter implements QueryBuilderProtoConverter {
+
+    /**
+     * Default constructor for NestedQueryBuilderProtoConverter.
+     */
+    public NestedQueryBuilderProtoConverter() {}
+
+    private QueryBuilderProtoConverterRegistry registry;
+
+    @Override
+    public void setRegistry(QueryBuilderProtoConverterRegistry registry) {
+        this.registry = registry;
+        // The utility class no longer stores the registry statically, it's passed directly to fromProto
+    }
+
+    @Override
+    public QueryContainer.QueryContainerCase getHandledQueryCase() {
+        return QueryContainer.QueryContainerCase.NESTED;
+    }
+
+    @Override
+    public QueryBuilder fromProto(QueryContainer queryContainer) {
+        if (queryContainer == null || queryContainer.getQueryContainerCase() != QueryContainer.QueryContainerCase.NESTED) {
+            throw new IllegalArgumentException("QueryContainer must contain a NestedQuery");
+        }
+        return NestedQueryBuilderProtoUtils.fromProto(queryContainer.getNested(), registry);
+    }
+}

modules/transport-grpc/src/main/java/org/opensearch/transport/grpc/proto/request/search/query/NestedQueryBuilderProtoUtils.java

@@ -0,0 +1,123 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.transport.grpc.proto.request.search.query;
+
+import org.apache.lucene.search.join.ScoreMode;
+import org.opensearch.index.query.AbstractQueryBuilder;
+import org.opensearch.index.query.InnerHitBuilder;
+import org.opensearch.index.query.NestedQueryBuilder;
+import org.opensearch.index.query.QueryBuilder;
+import org.opensearch.protobufs.ChildScoreMode;
+import org.opensearch.protobufs.NestedQuery;
+import org.opensearch.protobufs.QueryContainer;
+import org.opensearch.transport.grpc.proto.request.search.InnerHitsBuilderProtoUtils;
+import org.opensearch.transport.grpc.spi.QueryBuilderProtoConverterRegistry;
+
+/**
+ * Utility class for converting protobuf NestedQuery to OpenSearch NestedQueryBuilder.
+ * Handles the conversion of nested query protobuf messages to OpenSearch NestedQueryBuilder objects.
+ */
+class NestedQueryBuilderProtoUtils {
+
+    private NestedQueryBuilderProtoUtils() {
+        // Utility class, no instances
+    }
+
+    /**
+     * Converts a protobuf NestedQuery to an OpenSearch NestedQueryBuilder.
+     * Similar to {@link NestedQueryBuilder#fromXContent(org.opensearch.core.xcontent.XContentParser)}, this method
+     * parses the Protocol Buffer representation and creates a properly configured
+     * NestedQueryBuilder with the appropriate path, query, score mode, inner hits, boost, and query name.
+     *
+     * @param nestedQueryProto the protobuf NestedQuery to convert
+     * @param registry The registry to use for converting nested queries
+     * @return the converted OpenSearch NestedQueryBuilder
+     * @throws IllegalArgumentException if the protobuf query is invalid
+     */
+    static NestedQueryBuilder fromProto(NestedQuery nestedQueryProto, QueryBuilderProtoConverterRegistry registry) {
+        if (nestedQueryProto == null) {
+            throw new IllegalArgumentException("NestedQuery cannot be null");
+        }
+
+        float boost = AbstractQueryBuilder.DEFAULT_BOOST;
+        ScoreMode scoreMode = ScoreMode.Avg;
+        String queryName = null;
+        QueryBuilder query = null;
+        InnerHitBuilder innerHitBuilder = null;
+        boolean ignoreUnmapped = NestedQueryBuilder.DEFAULT_IGNORE_UNMAPPED;
+
+        String path = nestedQueryProto.getPath();
+        if (path.isEmpty()) {
+            throw new IllegalArgumentException("Path is required for NestedQuery");
+        }
+
+        if (!nestedQueryProto.hasQuery()) {
+            throw new IllegalArgumentException("Query is required for NestedQuery");
+        }
+        try {
+            QueryContainer queryContainer = nestedQueryProto.getQuery();
+            query = registry.fromProto(queryContainer);
+        } catch (Exception e) {
+            throw new IllegalArgumentException("Failed to convert inner query for NestedQuery: " + e.getMessage(), e);
+        }
+
+        if (nestedQueryProto.hasScoreMode()) {
+            scoreMode = parseScoreMode(nestedQueryProto.getScoreMode());
+        }
+
+        if (nestedQueryProto.hasIgnoreUnmapped()) {
+            ignoreUnmapped = nestedQueryProto.getIgnoreUnmapped();
+        }
+
+        if (nestedQueryProto.hasBoost()) {
+            boost = nestedQueryProto.getBoost();
+        }
+
+        if (nestedQueryProto.hasXName()) {
+            queryName = nestedQueryProto.getXName();
+        }
+
+        if (nestedQueryProto.hasInnerHits()) {
+            try {
+                innerHitBuilder = InnerHitsBuilderProtoUtils.fromProto(nestedQueryProto.getInnerHits());
+            } catch (Exception e) {
+                throw new IllegalArgumentException("Failed to convert inner hits for NestedQuery: " + e.getMessage(), e);
+            }
+        }
+
+        NestedQueryBuilder queryBuilder = new NestedQueryBuilder(path, query, scoreMode, innerHitBuilder).ignoreUnmapped(ignoreUnmapped)
+            .queryName(queryName)
+            .boost(boost);
+
+        return queryBuilder;
+    }
+
+    /**
+     * Converts protobuf ChildScoreMode to Lucene ScoreMode.
+     *
+     * @param childScoreMode the protobuf ChildScoreMode
+     * @return the converted Lucene ScoreMode
+     */
+    private static ScoreMode parseScoreMode(ChildScoreMode childScoreMode) {
+        switch (childScoreMode) {
+            case CHILD_SCORE_MODE_AVG:
+                return ScoreMode.Avg;
+            case CHILD_SCORE_MODE_MAX:
+                return ScoreMode.Max;
+            case CHILD_SCORE_MODE_MIN:
+                return ScoreMode.Min;
+            case CHILD_SCORE_MODE_NONE:
+                return ScoreMode.None;
+            case CHILD_SCORE_MODE_SUM:
+                return ScoreMode.Total;
+            default:
+                return ScoreMode.Avg; // Default value
+        }
+    }
+}

modules/transport-grpc/src/main/java/org/opensearch/transport/grpc/proto/request/search/query/QueryBuilderProtoConverterRegistryImpl.java

@@ -55,9 +55,11 @@ protected void registerBuiltInConverters() {
         delegate.registerConverter(new ExistsQueryBuilderProtoConverter());
         delegate.registerConverter(new RegexpQueryBuilderProtoConverter());
         delegate.registerConverter(new WildcardQueryBuilderProtoConverter());
+        delegate.registerConverter(new NestedQueryBuilderProtoConverter());
 
         // Set the registry on all converters so they can access each other
         delegate.setRegistryOnAllConverters(this);
+
         logger.info("Registered {} built-in query converters", delegate.size());
     }