feat: add BM25 query

Bm25 does not implement ObjectFilter because Aggregation API does not support bm25.

Author: bevzzz

src/it/java/io/weaviate/integration/SearchITest.java

@@ -22,6 +22,7 @@
 import io.weaviate.client6.v1.api.collections.data.Reference;
 import io.weaviate.client6.v1.api.collections.query.GroupBy;
 import io.weaviate.client6.v1.api.collections.query.Metadata;
+import io.weaviate.client6.v1.api.collections.query.QueryMetadata;
 import io.weaviate.client6.v1.api.collections.query.QueryResponseGroup;
 import io.weaviate.client6.v1.api.collections.query.Where;
 import io.weaviate.client6.v1.api.collections.vectorindex.Hnsw;
@@ -255,4 +256,29 @@ public void testFetchObjectsWithFilters() throws IOException {
             hugeHat.metadata().uuid());
 
   }
+
+  @Test
+  public void testBm25() throws IOException {
+    var nsWords = ns("Words");
+
+    client.collections.create(nsWords,
+        collection -> collection
+            .properties(
+                Property.text("relevant"),
+                Property.text("irrelevant")));
+
+    var words = client.collections.use(nsWords);
+
+    /* notWant */ words.data.insert(Map.of("relevant", "elefant", "irrelevant", "dollar bill"));
+    var want = words.data.insert(Map.of("relevant", "a dime a dollar", "irrelevant", "euro"));
+
+    var dollarWorlds = words.query.bm25(
+        "dollar",
+        bm25 -> bm25.queryProperties("relevant"));
+
+    Assertions.assertThat(dollarWorlds.objects())
+        .hasSize(1)
+        .extracting(WeaviateObject::metadata).extracting(QueryMetadata::uuid)
+        .containsOnly(want.metadata().uuid());
+  }
 }

src/main/java/io/weaviate/client6/v1/api/collections/query/AbstractQueryClient.java

@@ -56,6 +56,32 @@ public GroupedResponseT fetchObjects(FetchObjects query, GroupBy groupBy) {
     return performRequest(query, groupBy);
   }
 
+  // BM25 queries -------------------------------------------------------------
+
+  public ResponseT bm25(String query) {
+    return bm25(Bm25.of(query));
+  }
+
+  public ResponseT bm25(String query, Function<Bm25.Builder, ObjectBuilder<Bm25>> fn) {
+    return bm25(Bm25.of(query, fn));
+  }
+
+  public ResponseT bm25(Bm25 query) {
+    return performRequest(query);
+  }
+
+  public GroupedResponseT bm25(String query, GroupBy groupBy) {
+    return bm25(Bm25.of(query), groupBy);
+  }
+
+  public GroupedResponseT bm25(String query, Function<Bm25.Builder, ObjectBuilder<Bm25>> fn, GroupBy groupBy) {
+    return bm25(Bm25.of(query, fn), groupBy);
+  }
+
+  public GroupedResponseT bm25(Bm25 query, GroupBy groupBy) {
+    return performRequest(query, groupBy);
+  }
+
   // NearVector queries -------------------------------------------------------
 
   public ResponseT nearVector(Float[] vector) {

src/main/java/io/weaviate/client6/v1/api/collections/query/Bm25.java

@@ -0,0 +1,59 @@
+package io.weaviate.client6.v1.api.collections.query;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.function.Function;
+
+import io.weaviate.client6.v1.internal.ObjectBuilder;
+import io.weaviate.client6.v1.internal.grpc.protocol.WeaviateProtoBaseSearch;
+import io.weaviate.client6.v1.internal.grpc.protocol.WeaviateProtoSearchGet;
+
+public record Bm25(String query, List<String> queryProperties, BaseQueryOptions common)
+    implements SearchOperator {
+
+  public static final Bm25 of(String query) {
+    return of(query, ObjectBuilder.identity());
+  }
+
+  public static final Bm25 of(String query, Function<Builder, ObjectBuilder<Bm25>> fn) {
+    return fn.apply(new Builder(query)).build();
+  }
+
+  public Bm25(Builder builder) {
+    this(builder.query, builder.queryProperties, builder.baseOptions());
+  }
+
+  public static class Builder extends BaseQueryOptions.Builder<Builder, Bm25> {
+    // Required query parameters.
+    private final String query;
+
+    // Optional query parameters.
+    List<String> queryProperties;
+
+    public Builder(String query) {
+      this.query = query;
+    }
+
+    public Builder queryProperties(String... properties) {
+      return queryProperties(Arrays.asList(properties));
+    }
+
+    public Builder queryProperties(List<String> properties) {
+      this.queryProperties = properties;
+      return this;
+    }
+
+    @Override
+    public final Bm25 build() {
+      return new Bm25(this);
+    }
+  }
+
+  @Override
+  public final void appendTo(WeaviateProtoSearchGet.SearchRequest.Builder req) {
+    common.appendTo(req);
+    req.setBm25Search(WeaviateProtoBaseSearch.BM25.newBuilder()
+        .setQuery(query)
+        .addAllProperties(queryProperties));
+  }
+}