Fix bbq index feature exposure for testing & remove feature flag (#114832) (#114851)

We actually don't need a cluster feature, a capability added if the
feature flag is enabled is enough for testing.

closes #114787

(cherry picked from commit e87b894)

Co-authored-by: Elastic Machine <[email protected]>

Author: benwtrent

server/src/main/java/org/elasticsearch/index/mapper/MapperFeatures.java

@@ -9,7 +9,6 @@
 
 package org.elasticsearch.index.mapper;
 
-import org.elasticsearch.common.util.set.Sets;
 import org.elasticsearch.features.FeatureSpecification;
 import org.elasticsearch.features.NodeFeature;
 import org.elasticsearch.index.IndexSettings;
@@ -24,7 +23,7 @@
 public class MapperFeatures implements FeatureSpecification {
     @Override
     public Set<NodeFeature> getFeatures() {
-        Set<NodeFeature> features = Set.of(
+        return Set.of(
             IgnoredSourceFieldMapper.TRACK_IGNORED_SOURCE,
             PassThroughObjectMapper.PASS_THROUGH_PRIORITY,
             RangeFieldMapper.NULL_VALUES_OFF_BY_ONE_FIX,
@@ -47,13 +46,9 @@ public Set<NodeFeature> getFeatures() {
             IndexSettings.IGNORE_ABOVE_INDEX_LEVEL_SETTING,
             SourceFieldMapper.SYNTHETIC_SOURCE_COPY_TO_INSIDE_OBJECTS_FIX,
             TimeSeriesRoutingHashFieldMapper.TS_ROUTING_HASH_FIELD_PARSES_BYTES_REF,
-            FlattenedFieldMapper.IGNORE_ABOVE_WITH_ARRAYS_SUPPORT
+            FlattenedFieldMapper.IGNORE_ABOVE_WITH_ARRAYS_SUPPORT,
+            DenseVectorFieldMapper.BBQ_FORMAT
         );
-        // BBQ is currently behind a feature flag for testing
-        if (DenseVectorFieldMapper.BBQ_FEATURE_FLAG.isEnabled()) {
-            return Sets.union(features, Set.of(DenseVectorFieldMapper.BBQ_FORMAT));
-        }
-        return features;
     }
 
     @Override

server/src/main/java/org/elasticsearch/index/mapper/vectors/DenseVectorFieldMapper.java

@@ -36,7 +36,6 @@
 import org.apache.lucene.util.BytesRef;
 import org.apache.lucene.util.VectorUtil;
 import org.elasticsearch.common.ParsingException;
-import org.elasticsearch.common.util.FeatureFlag;
 import org.elasticsearch.common.xcontent.support.XContentMapValues;
 import org.elasticsearch.features.NodeFeature;
 import org.elasticsearch.index.IndexVersion;
@@ -110,7 +109,6 @@ public static boolean isNotUnitVector(float magnitude) {
     public static final NodeFeature INT4_QUANTIZATION = new NodeFeature("mapper.vectors.int4_quantization");
     public static final NodeFeature BIT_VECTORS = new NodeFeature("mapper.vectors.bit_vectors");
     public static final NodeFeature BBQ_FORMAT = new NodeFeature("mapper.vectors.bbq");
-    public static final FeatureFlag BBQ_FEATURE_FLAG = new FeatureFlag("bbq_index_format");
 
     public static final IndexVersion MAGNITUDE_STORED_INDEX_VERSION = IndexVersions.V_7_5_0;
     public static final IndexVersion INDEXED_BY_DEFAULT_INDEX_VERSION = IndexVersions.FIRST_DETACHED_INDEX_VERSION;
@@ -2259,9 +2257,6 @@ private static IndexOptions parseIndexOptions(String fieldName, Object propNode)
             throw new MapperParsingException("Unknown vector index options type [" + type + "] for field [" + fieldName + "]");
         }
         VectorIndexType parsedType = vectorIndexType.get();
-        if ((parsedType == VectorIndexType.BBQ_FLAT || parsedType == VectorIndexType.BBQ_HNSW) && BBQ_FEATURE_FLAG.isEnabled() == false) {
-            throw new MapperParsingException("Unknown vector index options type [" + type + "] for field [" + fieldName + "]");
-        }
         return parsedType.parseIndexOptions(fieldName, indexOptionsMap);
     }
 

server/src/test/java/org/elasticsearch/index/mapper/vectors/DenseVectorFieldMapperTests.java

@@ -63,7 +63,6 @@
 
 import static org.apache.lucene.codecs.lucene99.Lucene99HnswVectorsFormat.DEFAULT_BEAM_WIDTH;
 import static org.apache.lucene.codecs.lucene99.Lucene99HnswVectorsFormat.DEFAULT_MAX_CONN;
-import static org.elasticsearch.index.mapper.vectors.DenseVectorFieldMapper.BBQ_FEATURE_FLAG;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.instanceOf;
@@ -1228,11 +1227,9 @@ public void testInvalidParameters() {
             e.getMessage(),
             containsString("Failed to parse mapping: Mapping definition for [field] has unsupported parameters:  [foo : {}]")
         );
-        List<String> floatOnlyQuantizations = new ArrayList<>(Arrays.asList("int4_hnsw", "int8_hnsw", "int8_flat", "int4_flat"));
-        if (BBQ_FEATURE_FLAG.isEnabled()) {
-            floatOnlyQuantizations.add("bbq_hnsw");
-            floatOnlyQuantizations.add("bbq_flat");
-        }
+        List<String> floatOnlyQuantizations = new ArrayList<>(
+            Arrays.asList("int4_hnsw", "int8_hnsw", "int8_flat", "int4_flat", "bbq_hnsw", "bbq_flat")
+        );
         for (String quantizationKind : floatOnlyQuantizations) {
             e = expectThrows(
                 MapperParsingException.class,
@@ -1964,7 +1961,6 @@ public void testKnnQuantizedHNSWVectorsFormat() throws IOException {
     }
 
     public void testKnnBBQHNSWVectorsFormat() throws IOException {
-        assumeTrue("BBQ vectors are not supported in the current version", BBQ_FEATURE_FLAG.isEnabled());
         final int m = randomIntBetween(1, DEFAULT_MAX_CONN + 10);
         final int efConstruction = randomIntBetween(1, DEFAULT_BEAM_WIDTH + 10);
         final int dims = randomIntBetween(64, 4096);
@@ -2003,7 +1999,6 @@ public void testKnnBBQHNSWVectorsFormat() throws IOException {
     }
 
     public void testInvalidVectorDimensionsBBQ() {
-        assumeTrue("BBQ vectors are not supported in the current version", BBQ_FEATURE_FLAG.isEnabled());
         for (String quantizedFlatFormat : new String[] { "bbq_hnsw", "bbq_flat" }) {
             MapperParsingException e = expectThrows(MapperParsingException.class, () -> createDocumentMapper(fieldMapping(b -> {
                 b.field("type", "dense_vector");