diff --git a/common/src/main/java/com/google/udmi/util/GeneralUtils.java b/common/src/main/java/com/google/udmi/util/GeneralUtils.java
index 67982a5b01..e64152ed33 100644
--- a/common/src/main/java/com/google/udmi/util/GeneralUtils.java
+++ b/common/src/main/java/com/google/udmi/util/GeneralUtils.java
@@ -61,14 +61,13 @@ public class GeneralUtils {
       .enable(SerializationFeature.INDENT_OUTPUT)
       .setDateFormat(new ISO8601DateFormat())
       .disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
-      .setSerializationInclusion(JsonInclude.Include.NON_NULL);
+      .setSerializationInclusion(Include.NON_NULL);
   public static final ObjectMapper OBJECT_MAPPER_RAW =
       OBJECT_MAPPER.copy()
           .enable(SerializationFeature.ORDER_MAP_ENTRIES_BY_KEYS)
           .enable(Feature.ALLOW_TRAILING_COMMA)
           .enable(Feature.STRICT_DUPLICATE_DETECTION)
-          .disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS)
-          .setSerializationInclusion(Include.NON_NULL);
+          .disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
   public static final ObjectMapper OBJECT_MAPPER_STRICT =
       OBJECT_MAPPER_RAW.copy()
           .enable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
diff --git a/common/src/main/java/com/google/udmi/util/SiteModel.java b/common/src/main/java/com/google/udmi/util/SiteModel.java
index 87f4743fea..cef15ed570 100644
--- a/common/src/main/java/com/google/udmi/util/SiteModel.java
+++ b/common/src/main/java/com/google/udmi/util/SiteModel.java
@@ -33,7 +33,6 @@
 import com.fasterxml.jackson.databind.node.ObjectNode;
 import com.fasterxml.jackson.databind.util.ISO8601DateFormat;
 import com.google.common.collect.ImmutableList;
-
 import com.google.daq.mqtt.util.ExceptionMap;
 import java.io.File;
 import java.util.Arrays;
@@ -71,8 +70,8 @@ public class SiteModel {
   public static final String DEVICES_DIR = "devices";
   public static final String REFLECTOR_DIR = "reflector";
   public static final String METADATA_JSON = "metadata.json";
-  public static final String EXTRA_DEVICES_BASE = "extras";
-  public static final String EXTRA_DEVICES_FORMAT = EXTRA_DEVICES_BASE + "/%s";
+  public static final String EXTRAS_DIR = "extras";
+  public static final String EXTRA_DEVICES_FORMAT = EXTRAS_DIR + "/%s";
   public static final String NORMALIZED_JSON = "metadata_norm.json";
   public static final String SITE_DEFAULTS_FILE = "site_defaults.json";
   public static final String REGISTRATION_SUMMARY_BASE = "out/registration_summary";
@@ -89,7 +88,6 @@ public class SiteModel {
   private static final Pattern IOT_CORE_PATTERN = Pattern.compile(
       "projects/(.*)/locations/(.*)/registries/(.*)/devices/(.*)");
   private static final Pattern MQTT_PATTERN = Pattern.compile("/r/(.*)/d/(.*)");
-  private static final String EXTRAS_DIR = "extras";
   private static final String CLOUD_IOT_CONFIG_JSON = "cloud_iot_config.json";
   private static final Pattern SPEC_PATTERN = Pattern.compile(
       "(//([a-z]+)/)?([a-z-]+)(/([a-z0-9]+))?");
diff --git a/udmis/src/main/java/com/google/bos/udmi/service/access/ImplicitIotAccessProvider.java b/udmis/src/main/java/com/google/bos/udmi/service/access/ImplicitIotAccessProvider.java
index 81c10bc681..7eea7051ae 100644
--- a/udmis/src/main/java/com/google/bos/udmi/service/access/ImplicitIotAccessProvider.java
+++ b/udmis/src/main/java/com/google/bos/udmi/service/access/ImplicitIotAccessProvider.java
@@ -11,9 +11,11 @@
 import static com.google.udmi.util.GeneralUtils.ifNullThen;
 import static com.google.udmi.util.GeneralUtils.ifTrueThen;
 import static com.google.udmi.util.GeneralUtils.isNullOrNotEmpty;
+import static com.google.udmi.util.GeneralUtils.requireNull;
 import static com.google.udmi.util.JsonUtil.asMap;
 import static com.google.udmi.util.JsonUtil.isoConvert;
 import static com.google.udmi.util.JsonUtil.stringify;
+import static com.google.udmi.util.JsonUtil.stringifyTerse;
 import static java.lang.String.format;
 import static java.util.Objects.requireNonNull;
 import static java.util.Optional.ofNullable;
@@ -201,6 +203,8 @@ private Map<String, String> toDeviceMap(CloudModel cloudModel, String createdAt)
     ifNotNullThen(createdAt, x -> properties.put(CREATED_AT_PROPERTY, createdAt));
     properties.put(RESOURCE_TYPE_PROPERTY,
         ofNullable(cloudModel.resource_type).orElse(DEVICE).toString());
+    requireNull(cloudModel.metadata_str, "unexpected metadata_str content");
+    properties.put(METADATA_STR_KEY, stringifyTerse(cloudModel.metadata));
     properties.put(BLOCKED_PROPERTY, booleanString(cloudModel.blocked));
     ifNotNullThen(cloudModel.num_id, id -> properties.put(NUM_ID_PROPERTY, id));
     ifTrueThen(!cloudModel.credentials.isEmpty(), () -> {
diff --git a/validator/src/main/java/com/google/daq/mqtt/registrar/Registrar.java b/validator/src/main/java/com/google/daq/mqtt/registrar/Registrar.java
index f7aee21537..559f91564d 100644
--- a/validator/src/main/java/com/google/daq/mqtt/registrar/Registrar.java
+++ b/validator/src/main/java/com/google/daq/mqtt/registrar/Registrar.java
@@ -817,7 +817,7 @@ private CloudModel processExtra(String extraName, AtomicInteger alreadyBlocked)
   }
 
   private void reapExtraDevices(Set<String> current) {
-    File extrasDir = new File(siteDir, SiteModel.EXTRA_DEVICES_BASE);
+    File extrasDir = new File(siteDir, SiteModel.EXTRAS_DIR);
     String[] existing = ofNullable(extrasDir.list()).orElse(new String[0]);
     Set<String> previous = Arrays.stream(existing).collect(Collectors.toSet());
     difference(previous, current).forEach(expired -> {