[8.19] Fix broken bwc logic in text field mapper introduced by #129126 (#129308) (#129323)

* Fix broken bwc logic in text field mapper introduced by #129126 (#129308)

A missing condition in the bwc logic caused a text field to be a stored, while before #129126, this wasn't the case.

* fix test compile errors

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

@@ -316,7 +316,7 @@ public final class TextFieldMapper extends FieldMapper {
                         && this.withinMultiField == false
                         && multiFieldsBuilder.hasSyntheticSourceCompatibleKeywordField() == false;
                 } else {
-                    return isSyntheticSourceEnabled;
+                    return isSyntheticSourceEnabled && multiFieldsBuilder.hasSyntheticSourceCompatibleKeywordField() == false;
                 }
             });
             this.indexCreatedVersion = indexCreatedVersion;

server/src/test/java/org/elasticsearch/index/mapper/TextFieldMapperTests.java

@@ -51,6 +51,7 @@ import org.elasticsearch.common.lucene.search.MultiPhrasePrefixQuery;
 import org.elasticsearch.index.IndexMode;
 import org.elasticsearch.index.IndexSettings;
 import org.elasticsearch.index.IndexVersion;
+import org.elasticsearch.index.IndexVersions;
 import org.elasticsearch.index.analysis.AnalyzerScope;
 import org.elasticsearch.index.analysis.CharFilterFactory;
 import org.elasticsearch.index.analysis.CustomAnalyzer;
@@ -350,6 +351,31 @@ public class TextFieldMapperTests extends MapperTestCase {
         assertThat(fieldType.stored(), is(false));
     }
 
+    public void testStoreParameterDefaultsSyntheticSourceWithKeywordMultiFieldBwc() throws IOException {
+        var indexSettingsBuilder = getIndexSettingsBuilder();
+        indexSettingsBuilder.put(IndexSettings.INDEX_MAPPER_SOURCE_MODE_SETTING.getKey(), "synthetic");
+        var indexSettings = indexSettingsBuilder.build();
+
+        var mapping = mapping(b -> {
+            b.startObject("name");
+            b.field("type", "text");
+            b.startObject("fields");
+            b.startObject("keyword");
+            b.field("type", "keyword");
+            b.endObject();
+            b.endObject();
+            b.endObject();
+        });
+        IndexVersion beforeVersion = IndexVersions.INDEX_INT_SORT_INT_TYPE_8_19;
+        DocumentMapper mapper = createMapperService(beforeVersion, indexSettings, mapping).documentMapper();
+
+        var source = source(b -> b.field("name", "quick brown fox"));
+        ParsedDocument doc = mapper.parse(source);
+        List<IndexableField> fields = doc.rootDoc().getFields("name");
+        IndexableFieldType fieldType = fields.get(0).fieldType();
+        assertThat(fieldType.stored(), is(false));
+    }
+
     public void testStoreParameterDefaultsSyntheticSourceTextFieldIsMultiField() throws IOException {
         var indexSettingsBuilder = getIndexSettingsBuilder();
         indexSettingsBuilder.put(IndexSettings.INDEX_MAPPER_SOURCE_MODE_SETTING.getKey(), "synthetic");
@@ -374,6 +400,31 @@ public class TextFieldMapperTests extends MapperTestCase {
         assertThat(fieldType.stored(), is(false));
     }
 
+    public void testStoreParameterDefaultsSyntheticSourceTextFieldIsMultiFieldBwc() throws IOException {
+        var indexSettingsBuilder = getIndexSettingsBuilder();
+        indexSettingsBuilder.put(IndexSettings.INDEX_MAPPER_SOURCE_MODE_SETTING.getKey(), "synthetic");
+        var indexSettings = indexSettingsBuilder.build();
+
+        var mapping = mapping(b -> {
+            b.startObject("name");
+            b.field("type", "keyword");
+            b.startObject("fields");
+            b.startObject("text");
+            b.field("type", "text");
+            b.endObject();
+            b.endObject();
+            b.endObject();
+        });
+        IndexVersion beforeVersion = IndexVersions.INDEX_INT_SORT_INT_TYPE_8_19;
+        DocumentMapper mapper = createMapperService(beforeVersion, indexSettings, mapping).documentMapper();
+
+        var source = source(b -> b.field("name", "quick brown fox"));
+        ParsedDocument doc = mapper.parse(source);
+        List<IndexableField> fields = doc.rootDoc().getFields("name.text");
+        IndexableFieldType fieldType = fields.get(0).fieldType();
+        assertThat(fieldType.stored(), is(true));
+    }
+
     public void testBWCSerialization() throws IOException {
         MapperService mapperService = createMapperService(fieldMapping(b -> {
             b.field("type", "text");