Set event source for group variable changes to the variable name (#2231)

Author: scooterboo

src/main/java/emu/grasscutter/scripts/ScriptLib.java

@@ -403,7 +403,7 @@ public int SetGroupVariableValue(String var, int value) {
 
         val old = variables.getOrDefault(var, value);
         variables.put(var, value);
-        getSceneScriptManager().callEvent(new ScriptArgs(groupId, EventType.EVENT_VARIABLE_CHANGE, value, old));
+        getSceneScriptManager().callEvent(new ScriptArgs(groupId, EventType.EVENT_VARIABLE_CHANGE, value, old).setEventSource(var));
         return 0;
     }
 
@@ -418,7 +418,7 @@ public LuaValue ChangeGroupVariableValue(String var, int value) {
         variables.put(var, old + value);
         logger.debug("[LUA] Call ChangeGroupVariableValue with {},{}",
             old, old+value);
-        getSceneScriptManager().callEvent(new ScriptArgs(groupId, EventType.EVENT_VARIABLE_CHANGE, old+value, old));
+        getSceneScriptManager().callEvent(new ScriptArgs(groupId, EventType.EVENT_VARIABLE_CHANGE, old+value, old).setEventSource(var));
         return LuaValue.ZERO;
     }