fix: include subtable id in serialized output (#74)

Author: kodacme

src/main/java/com/kintone/client/RecordSerializer.java

@@ -253,6 +253,9 @@ private void writeSubtable(JsonGenerator gen, String fieldCode, List<TableRow> r
         gen.writeArrayFieldStart("value");
         for (TableRow row : rows) {
             gen.writeStartObject();
+            if (row.getId() != null) {
+                gen.writeNumberField("id", row.getId());
+            }
             gen.writeObjectFieldStart("value");
             writeTableRow(row, gen);
             gen.writeEndObject();

src/test/java/com/kintone/client/RecordSerializerTest.java

@@ -417,6 +417,28 @@ public void serialize_SUBTABLE_empty() throws IOException {
         assertThat(json).isEqualTo("{\"table\":{\"value\":[]}}");
     }
 
+    @Test
+    public void serialize_SUBTABLE_withId() throws IOException {
+        TableRow row1 = new TableRow(123L).putField("text", new SingleLineTextFieldValue("test 1"));
+        TableRow row2 = new TableRow(456L).putField("text", new SingleLineTextFieldValue("test 2"));
+        Record record = new Record().putField("table", new SubtableFieldValue(row1, row2));
+        String json = mapper.writeValueAsString(record);
+        assertThat(json)
+                .isEqualTo(
+                        "{\"table\":{\"value\":[{\"id\":123,\"value\":{\"text\":{\"value\":\"test 1\"}}},{\"id\":456,\"value\":{\"text\":{\"value\":\"test 2\"}}}]}}");
+    }
+
+    @Test
+    public void serialize_SUBTABLE_withAndWithoutId() throws IOException {
+        TableRow row1 = new TableRow(123L).putField("text", new SingleLineTextFieldValue("with id"));
+        TableRow row2 = new TableRow().putField("text", new SingleLineTextFieldValue("without id"));
+        Record record = new Record().putField("table", new SubtableFieldValue(row1, row2));
+        String json = mapper.writeValueAsString(record);
+        assertThat(json)
+                .isEqualTo(
+                        "{\"table\":{\"value\":[{\"id\":123,\"value\":{\"text\":{\"value\":\"with id\"}}},{\"value\":{\"text\":{\"value\":\"without id\"}}}]}}");
+    }
+
     @Test
     public void serialize_TIME() throws IOException {
         Record record = new Record().putField("time", new TimeFieldValue(LocalTime.of(0, 0)));