Add PaperKnownCommandsProvider for Paper 1.11.2+

Essentials/src/com/earth2me/essentials/Essentials.java

@@ -284,7 +284,11 @@ public void onEnable() {
                 }
 
                 //Known Commands Provider
-                knownCommandsProvider = new ReflKnownCommandsProvider();
+                if (PaperLib.isPaper() && VersionUtil.getServerBukkitVersion().isHigherThanOrEqualTo(VersionUtil.v1_12_2_R01)) {
+                    knownCommandsProvider = new PaperKnownCommandsProvider();
+                } else {
+                    knownCommandsProvider = new ReflKnownCommandsProvider();
+                }
 
                 execTimer.mark("Init(Providers)");
                 reload();

providers/PaperProvider/src/net/ess3/provider/providers/PaperKnownCommandsProvider.java

@@ -0,0 +1,19 @@
+package net.ess3.provider.providers;
+
+import net.ess3.provider.KnownCommandsProvider;
+import org.bukkit.Bukkit;
+import org.bukkit.command.Command;
+
+import java.util.Map;
+
+public class PaperKnownCommandsProvider implements KnownCommandsProvider {
+    @Override
+    public Map<String, Command> getKnownCommands() {
+        return Bukkit.getCommandMap().getKnownCommands();
+    }
+
+    @Override
+    public String getDescription() {
+        return "Paper Known Commands Provider";
+    }
+}