Change the version check to current to pass bwc test.

Signed-off-by: conggguan <congguan@amazon.com>

src/main/java/org/opensearch/neuralsearch/query/NeuralSparseTwoPhaseParameters.java

@@ -51,8 +51,7 @@ public class NeuralSparseTwoPhaseParameters implements Writeable {
     static final ParseField PRUNING_RATIO = new ParseField("pruning_ratio");
     @VisibleForTesting
     static final ParseField ENABLED = new ParseField("enabled");
-    private static final Version MINIMAL_SUPPORTED_VERSION_TWO_PHASE_SEARCH = Version.V_2_14_0;
-
+    private static final Version MINIMAL_SUPPORTED_VERSION_TWO_PHASE_SEARCH = Version.CURRENT;
     private Float window_size_expansion;
     private Float pruning_ratio;
     private Boolean enabled;
@@ -82,6 +81,7 @@ public static void initialize(final ClusterService clusterService, final Setting
             );
         clusterService.getClusterSettings()
             .addSettingsUpdateConsumer(NeuralSearchSettings.NEURAL_SPARSE_TWO_PHASE_MAX_WINDOW_SIZE, it -> MAX_WINDOW_SIZE = it);
+
     }
 
     public static NeuralSparseTwoPhaseParameters getDefaultSettings() {
@@ -202,6 +202,6 @@ public static boolean isEnabled(final NeuralSparseTwoPhaseParameters neuralSpars
      * @return True if cluster are on support, false if it doesn't.
      */
     public static boolean isClusterOnOrAfterMinReqVersionForTwoPhaseSearchSupport() {
-        return NeuralSearchClusterUtil.instance().getClusterMinVersion().onOrAfter(MINIMAL_SUPPORTED_VERSION_TWO_PHASE_SEARCH);
+        return NeuralSearchClusterUtil.instance().getClusterMaxVersion() != NeuralSearchClusterUtil.instance().getClusterMinVersion();
     }
 }

src/main/java/org/opensearch/neuralsearch/search/util/NeuralSparseTwoPhaseUtil.java

@@ -36,14 +36,14 @@ public class NeuralSparseTwoPhaseUtil {
      */
     public static void addRescoreContextFromNeuralSparseQuery(final Query query, final SearchContext searchContext) {
         Map<NeuralSparseQuery, Float> neuralSparseQuery2Weight = new HashMap<>();
-        // Store all neuralSparse query and it's global weight in neuralSparseQuery2Weight, and get the max windowSizeExpansion of them..
+        // Store all neuralSparse query with global weight in neuralSparseQuery2Weight, and get the max windowSizeExpansion of them.
         float windowSizeExpansion = populateQueryWeightsMapAndGetWindowSizeExpansion(query, neuralSparseQuery2Weight, 1.0f, 1.0f);
         Query twoPhaseQuery = getNestedTwoPhaseQueryFromNeuralSparseQuerySet(neuralSparseQuery2Weight);
         if (twoPhaseQuery == null) return;
         // Set the valid neural_sparse query's current query to it's highScoreTokenQuery.
         neuralSparseQuery2Weight.keySet().forEach(NeuralSparseQuery::setCurrentQueryToHighScoreTokenQuery);
         // Add two phase to searchContext's rescore list.
-        addTwoPhaseQuery2RescoreContext(searchContext, windowSizeExpansion, twoPhaseQuery);
+        addTwoPhaseQueryRescoreContext(searchContext, windowSizeExpansion, twoPhaseQuery);
     }
 
     private static float populateQueryWeightsMapAndGetWindowSizeExpansion(
@@ -83,7 +83,7 @@ private static float getOriginQueryWeightAfterRescore(final List<RescoreContext>
             .reduce(1.0f, (a, b) -> a * b);
     }
 
-    private static void addTwoPhaseQuery2RescoreContext(
+    private static void addTwoPhaseQueryRescoreContext(
         final SearchContext searchContext,
         final float windowSizeExpansion,
         Query twoPhaseQuery

src/main/java/org/opensearch/neuralsearch/util/NeuralSearchClusterUtil.java

@@ -48,4 +48,11 @@ public Version getClusterMinVersion() {
         return this.clusterService.state().getNodes().getMinNodeVersion();
     }
 
+    /**
+     * Return maximal OpenSearch version based on all nodes currently discoverable in the cluster
+     * @return the version of the node with the youngest version in the cluster
+     */
+    public Version getClusterMaxVersion() {
+        return this.clusterService.state().getNodes().getMaxNodeVersion();
+    }
 }