Возвращаем rarity, fuel и category ибо они нужны движку

src/main/kotlin/ru/dbotthepony/kstarbound/defs/item/IItemDefinition.kt

@@ -18,6 +18,11 @@ interface IItemDefinition : IThingWithDescription {
 	 */
 	val price: Long
 
+	/**
+	 * Редкость предмета
+	 */
+	val rarity: ItemRarity
+
 	/**
 	 * Категория предмета, определяет, в какую вкладку инвентаря оно попадает
 	 */
@@ -48,6 +53,11 @@ interface IItemDefinition : IThingWithDescription {
 	 */
 	val eventCategory: String?
 
+	/**
+	 * Топливо корабля
+	 */
+	val fuelAmount: Long
+
 	/**
 	 * Заставляет предмет "использовать" сразу же при подборе
 	 */

src/main/kotlin/ru/dbotthepony/kstarbound/defs/item/ItemPrototype.kt

@@ -28,12 +28,12 @@ open class ItemPrototype : FreezableDefintionBuilder(), IItemDefinition {
 		get() = descriptionData.racialShortDescription
 
 	@JsonPropertyConfig(isFlat = true)
-	var descriptionData: ThingDescription by NotNullVar()
+	var descriptionData: ThingDescription by NotNull()
 
 	final override var itemName: String by NotNull()
 	final override var price: Long by NotNull(0L)
 	final override var rarity: ItemRarity by NotNull(ItemRarity.COMMON)
-	final override var category: String? by Nullable()
+	final override var category: String by NotNull()
 	final override var inventoryIcon: ImmutableList<InventoryIcon>? by Nullable()
 	final override var itemTags: ImmutableList<String> by NotNull(ImmutableList.of())
 	final override var learnBlueprintsOnPickup: ImmutableList<RegistryReference<IItemDefinition>> by NotNull(ImmutableList.of())
@@ -44,7 +44,7 @@ open class ItemPrototype : FreezableDefintionBuilder(), IItemDefinition {
 	final override var tooltipKind: String by NotNull("normal")
 	final override var twoHanded: Boolean by NotNull(false)
 	final override var radioMessagesOnPickup: ImmutableList<String> by NotNull(ImmutableList.of())
-	final override var fuelAmount: Long? by Nullable()
+	final override var fuelAmount: Long by NotNull(0L)
 
 	final override var pickupSoundsSmall: ImmutableList<String> by NotNull(ImmutableList.of())
 	final override var pickupSoundsMedium: ImmutableList<String> by NotNull(ImmutableList.of())

src/main/kotlin/ru/dbotthepony/kstarbound/defs/item/ItemRarity.kt

@@ -0,0 +1,20 @@
+package ru.dbotthepony.kstarbound.defs.item
+
+import com.google.gson.stream.JsonWriter
+import ru.dbotthepony.kstarbound.io.json.builder.IStringSerializable
+
+enum class ItemRarity(val canonical: String) : IStringSerializable {
+	COMMON("Common"),
+	UNCOMMON("Uncommon"),
+	RARE("Rare"),
+	LEGENDARY("Legendary"),
+	ESSENTIAL("Essential");
+
+	override fun match(name: String): Boolean {
+		return name == this.canonical || name.lowercase() == this.name.lowercase()
+	}
+
+	override fun write(out: JsonWriter) {
+		out.value(canonical)
+	}
+}