pluginsLatch

Gates buildClasspath on a host that has plugins — not on their jars, which are all loaded before any is enabled, but on the urls a plugin attaches to its own loader inside onEnable, which PluginJarCollector reads live. Opened by MixinDedicatedServer at initServer's RETURN, by paper's ServerLoadEvent listener, or here at warmup start where there is no Bukkit layer. Untimed: no constant tells a slow startup from a signal that will never come, so mcp.plugins.gate=false is the way past one that never does.