Removed empty objects from json serialization with equality instead of post-hoc string replace - kudos @SomeTroglodyte

core/src/com/unciv/logic/files/UncivFiles.kt

@@ -428,14 +428,7 @@ class UncivFiles(
             game.version = GameInfo.CURRENT_COMPATIBILITY_VERSION
 
             if (updateChecksum) game.checksum = game.calculateChecksum()
-            var plainJson = json().toJson(game)
-
-            val removeableStrings = listOf(
-                ",\"history\":{}", // empty history object in tile
-                ",\"promotions\":{}", // empty promotions object in unit
-            )
-            for (removableString in removeableStrings)
-                plainJson = plainJson.replace(removableString,"")
+            val plainJson = json().toJson(game)
 
             return if (forceZip ?: saveZipped) Gzip.zip(plainJson) else plainJson
         }

core/src/com/unciv/logic/map/mapunit/UnitPromotions.kt

@@ -137,4 +137,10 @@ class UnitPromotions : IsPartOfGameInfoSerialization {
         toReturn.unit = unit
         return toReturn
     }
+
+    // For json serialization, to not serialize an empty object
+    override fun equals(other: Any?): Boolean {
+        if (other !is UnitPromotions) return false
+        return XP == other.XP && promotions == other.promotions && numberOfPromotions == other.numberOfPromotions
+    }
 }

core/src/com/unciv/logic/map/tile/TileHistory.kt

@@ -31,7 +31,7 @@ class TileHistory(
 
             companion object {
                 fun deserialize(s: String): CityCenterType =
-                        values().firstOrNull { it.serializedRepresentation == s } ?: None
+                        entries.firstOrNull { it.serializedRepresentation == s } ?: None
             }
         }
 
@@ -91,4 +91,13 @@ class TileHistory(
 
     @VisibleForTesting
     override fun iterator() = history.iterator()
+
+    // For json serialization, to not serialize an empty object
+    override fun equals(other: Any?): Boolean {
+        if (other !is TileHistory) return false
+        if (history == other.history) return true
+        return history.size == other.history.size && history.entries.all { (turn, state) ->
+            state == other.history[turn]
+        }
+    }
 }