Preserve Java version when merging Fabric metadata

Author: realdoomsboygaming

Natives/MinecraftResourceDownloadTask.m

@@ -202,12 +202,20 @@ - (void)downloadVersionMetadata:(NSDictionary *)version success:(void (^)())succ
         }
 
         if (localInheritedVersion) {
+            id inheritedJavaVersion = metadata[@"javaVersion"];
             [MinecraftResourceUtils processVersion:localInheritedVersion inheritsFrom:metadata];
+            if ([inheritedJavaVersion isKindOfClass:NSDictionary.class]) {
+                metadata[@"javaVersion"] = inheritedJavaVersion;
+            }
             self.metadata = metadata;
         } else if (metadata[@"inheritsFrom"]) {
             NSMutableDictionary *inheritsFromDict = parseJSONFromFile([NSString stringWithFormat:@"%1$s/versions/%2$@/%2$@.json", getenv("POJAV_GAME_DIR"), metadata[@"inheritsFrom"]]);
             if (inheritsFromDict) {
+                id inheritedJavaVersion = inheritsFromDict[@"javaVersion"];
                 [MinecraftResourceUtils processVersion:metadata inheritsFrom:inheritsFromDict];
+                if ([inheritedJavaVersion isKindOfClass:NSDictionary.class]) {
+                    inheritsFromDict[@"javaVersion"] = inheritedJavaVersion;
+                }
                 self.metadata = inheritsFromDict;
             } else {
                 self.metadata = metadata;

Natives/MinecraftResourceUtils.m

@@ -44,8 +44,12 @@ + (void)processVersion:(NSMutableDictionary *)json inheritsFrom:(NSMutableDictio
 
 + (void)insertSafety:(NSMutableDictionary *)targetVer from:(NSDictionary *)fromVer arr:(NSArray *)arr {
     for (NSString *key in arr) {
-        if (([fromVer[key] isKindOfClass:NSString.class] && [fromVer[key] length] > 0) || targetVer[key] == nil) {
-            targetVer[key] = fromVer[key];
+        id value = fromVer[key];
+        if (!value || value == NSNull.null) {
+            continue;
+        }
+        if (([value isKindOfClass:NSString.class] && [value length] > 0) || targetVer[key] == nil) {
+            targetVer[key] = value;
         } else {
             NSLog(@"[MCDL] insertSafety: how to insert %@?", key);
         }