diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/filestructurefinder/FileStructureUtils.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/filestructurefinder/FileStructureUtils.java
index 24a29f11e4355..90cc74c8d259c 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/filestructurefinder/FileStructureUtils.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/filestructurefinder/FileStructureUtils.java
@@ -187,11 +187,8 @@ static Tuple<SortedMap<String, Object>, SortedMap<String, FieldStats>> guessMapp
 
         for (String fieldName : uniqueFieldNames) {
 
-            List<Object> fieldValues = sampleRecords.stream().flatMap(record -> {
-                    Object fieldValue = record.get(fieldName);
-                    return (fieldValue == null) ? Stream.empty() : Stream.of(fieldValue);
-                }
-            ).collect(Collectors.toList());
+            List<Object> fieldValues = sampleRecords.stream().map(record -> record.get(fieldName)).filter(fieldValue -> fieldValue != null)
+                .collect(Collectors.toList());
 
             Tuple<Map<String, String>, FieldStats> mappingAndFieldStats =
                 guessMappingAndCalculateFieldStats(explanation, fieldName, fieldValues, timeoutChecker);