Configure keeping source in FieldMapper

docs/changelog/112706.yaml

@@ -0,0 +1,5 @@
+pr: 112706
+summary: Configure keeping source in `FieldMapper`
+area: Mapping
+type: enhancement
+issues: []

modules/data-streams/src/javaRestTest/java/org/elasticsearch/datastreams/logsdb/qa/matchers/source/SourceMatcher.java

@@ -179,7 +179,9 @@ private Optional<MatchResult> matchWithFieldSpecificMatcher(String fieldName, Li
 
     // Checks for scenarios when source is stored exactly and therefore can be compared without special logic.
     private boolean sourceMatchesExactly(MappingTransforms.FieldMapping mapping, List<Object> expectedValues) {
-        return mapping.parentMappingParameters().stream().anyMatch(m -> m.getOrDefault("enabled", "true").equals("false"));
+        return mapping.parentMappingParameters().stream().anyMatch(m -> m.getOrDefault("enabled", "true").equals("false"))
+            || mapping.mappingParameters().getOrDefault("synthetic_source_keep", "none").equals("all")
+            || expectedValues.size() > 1 && mapping.mappingParameters().getOrDefault("synthetic_source_keep", "none").equals("arrays");
     }
 
     private MatchResult matchWithGenericMatcher(List<Object> actualValues, List<Object> expectedValues) {

modules/mapper-extras/src/main/java/org/elasticsearch/index/mapper/extras/MatchOnlyTextFieldMapper.java

@@ -433,7 +433,7 @@ public MatchOnlyTextFieldType fieldType() {
 
     @Override
     protected SyntheticSourceSupport syntheticSourceSupport() {
-        var loader = new StringStoredFieldFieldLoader(fieldType().storedFieldNameForSyntheticSource(), leafName()) {
+        var loader = new StringStoredFieldFieldLoader(fieldType().storedFieldNameForSyntheticSource(), fieldType().name(), leafName()) {
             @Override
             protected void write(XContentBuilder b, Object value) throws IOException {
                 b.value((String) value);

plugins/mapper-annotated-text/src/main/java/org/elasticsearch/index/mapper/annotatedtext/AnnotatedTextFieldMapper.java

@@ -582,7 +582,7 @@ protected void write(XContentBuilder b, Object value) throws IOException {
 
         var kwd = TextFieldMapper.SyntheticSourceHelper.getKeywordFieldMapperForSyntheticSource(this);
         if (kwd != null) {
-            return new SyntheticSourceSupport.Native(kwd.syntheticFieldLoader(leafName()));
+            return new SyntheticSourceSupport.Native(kwd.syntheticFieldLoader(fullPath(), leafName()));
         }
 
         return super.syntheticSourceSupport();