don't explicitly set the config if not present

Author: markjhoy

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

@@ -144,13 +144,10 @@ private static SparseVectorFieldMapper.IndexOptions getDefaultIndexOptions(Mappi
             return new IndexOptions(false, null);
         }
 
-        // index options are not set - for new indices, we
-        // need to set pruning to true by default
-        // with a default pruning configuration
-        return new IndexOptions(
-            true,
-            new PruningConfig(PruningConfig.DEFAULT_TOKENS_FREQ_RATIO_THRESHOLD, PruningConfig.DEFAULT_TOKENS_WEIGHT_THRESHOLD)
-        );
+        // index options are not set - for new indices,
+        // if this is null, in the query will use the
+        // proper defaults
+        return null;
     }
 
     private static SparseVectorFieldMapper.IndexOptions parseIndexOptions(MappingParserContext context, Object propNode) {

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/search/SparseVectorQueryBuilder.java

@@ -418,7 +418,15 @@ private IndexFieldPruningSettings getIndexFieldPruningSettings(SparseVectorField
 
         SparseVectorFieldMapper.IndexOptions indexOptions = sparseVectorFieldMapper.getIndexOptions();
         if (indexOptions == null) {
-            return new IndexFieldPruningSettings(null, null);
+            // return the default if not set in the index options
+            return new IndexFieldPruningSettings(
+                true,
+                new TokenPruningConfig(
+                    TokenPruningConfig.DEFAULT_TOKENS_FREQ_RATIO_THRESHOLD,
+                    TokenPruningConfig.DEFAULT_TOKENS_WEIGHT_THRESHOLD,
+                    false
+                )
+            );
         }
 
         Boolean indexOptionsPrune = indexOptions.getPrune();