Expose ZDT to the API

api/src/main/java/dev/plex/util/adapter/ZonedDateTimeAdapter.java

@@ -0,0 +1,31 @@
+package dev.plex.util.adapter;
+
+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;
+import java.lang.reflect.Type;
+import java.time.Instant;
+import java.time.ZoneId;
+import java.time.ZonedDateTime;
+
+public class ZonedDateTimeAdapter implements JsonSerializer<ZonedDateTime>, JsonDeserializer<ZonedDateTime>
+{
+    private static final ZoneId UTC = ZoneId.of("Etc/UTC");
+
+    @Override
+    public JsonElement serialize(ZonedDateTime src, Type typeOfSrc, JsonSerializationContext context)
+    {
+        return new JsonPrimitive(src.toInstant().toEpochMilli());
+    }
+
+    @Override
+    public ZonedDateTime deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException
+    {
+        Instant instant = Instant.ofEpochMilli(json.getAsJsonPrimitive().getAsLong());
+        return ZonedDateTime.ofInstant(instant, UTC);
+    }
+}