MultiMC instance lacks `legacy*` traits in the Minecraft component

[mineLdiver]

In the original generated json:

  "+traits": [
    "texturepacks",
    "FirstThreadOnMacOs"
  ],

This causes a crash with mods that interact with the crafting recipes sorter:

java.lang.ExceptionInInitializerError: null
	at net.minecraft.unmapped.C_95106612.m_49738346(C_95106612.java:103) ~[client-intermediary.jar:?]
	at net.minecraft.unmapped.C_95106612.m_06093942(C_95106612.java:82) ~[client-intermediary.jar:?]
	at net.minecraft.unmapped.C_81592558.<clinit>(C_81592558.java:223) ~[client-intermediary.jar:?]
	at net.minecraft.unmapped.C_19106855.<init>(C_19106855.java:14) ~[client-intermediary.jar:?]
	at net.minecraft.client.Minecraft.<init>(Minecraft.java:233) ~[client-intermediary.jar:?]
	at net.minecraft.unmapped.C_71402804.<init>(C_71402804.java:34) ~[client-intermediary.jar:?]
	at net.minecraft.client.MinecraftApplet.init(MinecraftApplet.java:34) ~[minecraft-b1.7.3-client.jar:?]
	at net.fabricmc.loader.impl.game.minecraft.applet.AppletLauncher.init(AppletLauncher.java:138) ~[fabric-loader-0.18.4.jar:?]
	at net.fabricmc.loader.impl.game.minecraft.applet.AppletFrame.launch(AppletFrame.java:127) ~[fabric-loader-0.18.4.jar:?]
	at net.fabricmc.loader.impl.game.minecraft.applet.AppletMain.run(AppletMain.java:44) ~[fabric-loader-0.18.4.jar:?]
	at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:318) ~[?:?]
	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:773) ~[?:?]
	at java.awt.EventQueue$4.run(EventQueue.java:720) ~[?:?]
	at java.awt.EventQueue$4.run(EventQueue.java:714) ~[?:?]
	at java.security.AccessController.doPrivileged(AccessController.java:400) ~[?:?]
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:87) ~[?:?]
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:742) ~[?:?]
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203) ~[?:?]
	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124) ~[?:?]
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113) ~[?:?]
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109) ~[?:?]
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101) ~[?:?]
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:90) ~[?:?]
Caused by: java.lang.IllegalArgumentException: Comparison method violates its general contract!
	at java.util.TimSort.mergeLo(TimSort.java:781) ~[?:?]
	at java.util.TimSort.mergeAt(TimSort.java:518) ~[?:?]
	at java.util.TimSort.mergeForceCollapse(TimSort.java:461) ~[?:?]
	at java.util.TimSort.sort(TimSort.java:254) ~[?:?]
	at java.util.Arrays.sort(Arrays.java:1308) ~[?:?]
	at java.util.ArrayList.sort(ArrayList.java:1804) ~[?:?]
	at java.util.Collections.sort(Collections.java:178) ~[?:?]
	at net.minecraft.unmapped.C_70737137.<init>(C_70737137.java:399) ~[client-intermediary.jar:?]
	at net.minecraft.unmapped.C_70737137.<clinit>(C_70737137.java:13) ~[client-intermediary.jar:?]
	... 23 more

Including the legacy* traits fixes the issue and allows the mods to run normally:

  "+traits": [
    "texturepacks",
    "FirstThreadOnMacOs",
    "legacyLaunch",
    "legacyServices"
  ],

[SpaceWalkerRS]

Thanks for the report. Just a few questions before I delve into this

• Is the Rust installer also affected by this issue?
• Are these traits relevant for only a subset of versions (e.g. 1.5.2 and below, or 1.12.2 and below)?

[DanyGames2014]

• Yes, the Rust Installer also omits these traits
• PrismLauncher applies legacyServices for r1.7.5 and below, this checks out with minecraft.wiki which lists this for the following r1.7.6 As a result of the old skin server being shut down, 1.7.6 is the oldest version of the game where skins still work without the use of modifications or third-party programs., legacyLaunch gets applied for r1.5.2 and below