Address review nits

Author: jordan-powers

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

@@ -362,10 +362,37 @@ public Query phrasePrefixQuery(TokenStream stream, int slop, int maxExpansions,
             return toQuery(query, queryShardContext);
         }
 
+        private static class BytesFromMixedStringsBytesRefBlockLoader extends BlockStoredFieldsReader.StoredFieldsBlockLoader {
+            BytesFromMixedStringsBytesRefBlockLoader(String field) {
+                super(field);
+            }
+
+            @Override
+            public Builder builder(BlockFactory factory, int expectedCount) {
+                return factory.bytesRefs(expectedCount);
+            }
+
+            @Override
+            public RowStrideReader rowStrideReader(LeafReaderContext context) throws IOException {
+                return new BlockStoredFieldsReader.Bytes(field) {
+                    private final BytesRef scratch = new BytesRef();
+
+                    @Override
+                    protected BytesRef toBytesRef(Object v) {
+                        if (v instanceof BytesRef) {
+                            return (BytesRef) v;
+                        } else {
+                            return BlockSourceReader.toBytesRef(scratch, (String) v);
+                        }
+                    }
+                };
+            }
+        }
+
         @Override
         public BlockLoader blockLoader(BlockLoaderContext blContext) {
             if (textFieldType.isSyntheticSource()) {
-                return new BlockStoredFieldsReader.BytesFromMixedStringsBytesRefBlockLoader(storedFieldNameForSyntheticSource());
+                return new BytesFromMixedStringsBytesRefBlockLoader(storedFieldNameForSyntheticSource());
             }
             SourceValueFetcher fetcher = SourceValueFetcher.toString(blContext.sourcePaths(name()));
             // MatchOnlyText never has norms, so we have to use the field names field
@@ -386,10 +413,11 @@ public IndexFieldData.Builder fielddataBuilder(FieldDataContext fieldDataContext
                 ) {
                     @Override
                     protected BytesRef storedToBytesRef(Object stored) {
-                        if (stored instanceof BytesRef) {
-                            return (BytesRef) stored;
+                        if (stored instanceof BytesRef storedBytes) {
+                            return storedBytes;
                         } else {
-                            return new BytesRef((String) stored);
+                            assert stored instanceof String;
+                            return new BytesRef(stored.toString());
                         }
                     }
                 };
@@ -481,10 +509,11 @@ protected SyntheticSourceSupport syntheticSourceSupport() {
             () -> new StringStoredFieldFieldLoader(fieldType().storedFieldNameForSyntheticSource(), fieldType().name(), leafName()) {
                 @Override
                 protected void write(XContentBuilder b, Object value) throws IOException {
-                    if (value instanceof BytesRef) {
-                        b.value(((BytesRef) value).utf8ToString());
+                    if (value instanceof BytesRef valueBytes) {
+                        b.value(valueBytes.utf8ToString());
                     } else {
-                        b.value((String) value);
+                        assert value instanceof String;
+                        b.value(value.toString());
                     }
                 }
             }

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

@@ -469,7 +469,7 @@ public String toString() {
     /**
      * Convert a {@link String} into a utf-8 {@link BytesRef}.
      */
-    static BytesRef toBytesRef(BytesRef scratch, String v) {
+    public static BytesRef toBytesRef(BytesRef scratch, String v) {
         int len = UnicodeUtil.maxUTF8Length(v.length());
         if (scratch.bytes.length < len) {
             scratch.bytes = new byte[len];

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

@@ -35,10 +35,10 @@ public boolean canReuse(int startingDocID) {
         return true;
     }
 
-    private abstract static class StoredFieldsBlockLoader implements BlockLoader {
+    public abstract static class StoredFieldsBlockLoader implements BlockLoader {
         protected final String field;
 
-        StoredFieldsBlockLoader(String field) {
+        public StoredFieldsBlockLoader(String field) {
             this.field = field;
         }
 
@@ -63,33 +63,6 @@ public final SortedSetDocValues ordinals(LeafReaderContext context) {
         }
     }
 
-    public static class BytesFromMixedStringsBytesRefBlockLoader extends StoredFieldsBlockLoader {
-        public BytesFromMixedStringsBytesRefBlockLoader(String field) {
-            super(field);
-        }
-
-        @Override
-        public Builder builder(BlockFactory factory, int expectedCount) {
-            return factory.bytesRefs(expectedCount);
-        }
-
-        @Override
-        public RowStrideReader rowStrideReader(LeafReaderContext context) throws IOException {
-            return new Bytes(field) {
-                private final BytesRef scratch = new BytesRef();
-
-                @Override
-                protected BytesRef toBytesRef(Object v) {
-                    if (v instanceof BytesRef) {
-                        return (BytesRef) v;
-                    } else {
-                        return BlockSourceReader.toBytesRef(scratch, (String) v);
-                    }
-                }
-            };
-        }
-    }
-
     /**
      * Load {@link BytesRef} blocks from stored {@link BytesRef}s.
      */
@@ -139,10 +112,10 @@ protected BytesRef toBytesRef(Object v) {
         }
     }
 
-    private abstract static class Bytes extends BlockStoredFieldsReader {
+    public abstract static class Bytes extends BlockStoredFieldsReader {
         private final String field;
 
-        Bytes(String field) {
+        public Bytes(String field) {
             this.field = field;
         }