[discovery] Fix Instant serialization/deserialization regression (#…

…4029)

* Fix Instant serialization/deserialization regression

Signed-off-by: Jacob Laursen <jacob-github@vindvejr.dk>

* Consolidate serialization and deserialization in same type adapter

Signed-off-by: Jacob Laursen <jacob-github@vindvejr.dk>

* Simplify deserializer

Signed-off-by: Jacob Laursen <jacob-github@vindvejr.dk>

---------

Signed-off-by: Jacob Laursen <jacob-github@vindvejr.dk>

bundles/org.openhab.core.storage.json/src/main/java/org/openhab/core/storage/json/internal/InstantTypeAdapter.java

@@ -0,0 +1,62 @@
+/**
+ * Copyright (c) 2010-2024 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.core.storage.json.internal;
+
+import java.lang.reflect.Type;
+import java.time.Instant;
+import java.time.format.DateTimeParseException;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+
+import com.google.gson.JsonDeserializationContext;
+import com.google.gson.JsonDeserializer;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonParseException;
+import com.google.gson.JsonPrimitive;
+import com.google.gson.JsonSerializationContext;
+import com.google.gson.JsonSerializer;
+
+/**
+ * The {@link InstantTypeAdapter} implements serialization and deserialization of {@link Instant}.
+ * as formatted UTC strings.
+ *
+ * Deserialization supports milliseconds since epoch as well.
+ *
+ * @author Jacob Laursen - Initial contribution
+ */
+@NonNullByDefault
+public class InstantTypeAdapter implements JsonSerializer<Instant>, JsonDeserializer<Instant> {
+    /**
+     * Converts an {@link Instant} to a formatted UTC string.
+     */
+    @Override
+    public JsonElement serialize(Instant instant, Type typeOfSrc, JsonSerializationContext context) {
+        return new JsonPrimitive(instant.toString());
+    }
+
+    /**
+     * Converts a formatted UTC string to {@link Instant}.
+     * As fallback, milliseconds since epoch is supported as well.
+     */
+    @Override
+    public @Nullable Instant deserialize(JsonElement element, Type arg1, JsonDeserializationContext arg2)
+            throws JsonParseException {
+        try {
+            return Instant.parse(element.getAsString());
+        } catch (DateTimeParseException e) {
+            // Fallback to milliseconds since epoch for backwards compatibility.
+            return Instant.ofEpochMilli(element.getAsLong());
+        }
+    }
+}

bundles/org.openhab.core.storage.json/src/main/java/org/openhab/core/storage/json/internal/JsonStorage.java

@@ -17,6 +17,7 @@
 import java.io.FileOutputStream;
 import java.io.FileReader;
 import java.io.IOException;
+import java.time.Instant;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
@@ -112,6 +113,7 @@ public JsonStorage(File file, @Nullable ClassLoader classLoader, int maxBackupFi
                 .registerTypeHierarchyAdapter(Map.class, new OrderingMapSerializer())//
                 .registerTypeHierarchyAdapter(Set.class, new OrderingSetSerializer())//
                 .registerTypeAdapter(Configuration.class, new ConfigurationDeserializer()) //
+                .registerTypeAdapter(Instant.class, new InstantTypeAdapter()) //
                 .setPrettyPrinting() //
                 .create();