Allow ping passthrough for descriptions too

proxy/src/main/java/com/velocitypowered/proxy/config/PingPassthroughMode.java

@@ -3,5 +3,6 @@ package com.velocitypowered.proxy.config;
 public enum PingPassthroughMode {
   DISABLED,
   MODS,
+  DESCRIPTION,
   ALL
 }

proxy/src/main/java/com/velocitypowered/proxy/config/VelocityConfiguration.java

@@ -90,14 +90,17 @@ public class VelocityConfiguration extends AnnotatedConfig implements ProxyConfi
   @Comment({
       "Should Velocity pass server list ping requests to a backend server?",
       "Available options:",
-      "- \"disabled\": No pass-through will be done. The velocity.toml and server-icon.png",
-      "              will determine the initial server list ping response.",
-      "- \"mods\":     Passes only the mod list from your backend server into the response.",
-      "              The first server in your try list (or forced host) with a mod list will be",
-      "              used. If no backend servers can be contacted, Velocity will not display any",
-      "              mod information.",
-      "- \"all\":      Passes everything from the backend server into the response. The Velocity",
-      "              configuration is used if no servers could be contacted."
+      "- \"disabled\":    No pass-through will be done. The velocity.toml and server-icon.png",
+      "                 will determine the initial server list ping response.",
+      "- \"mods\":        Passes only the mod list from your backend server into the response.",
+      "                 The first server in your try list (or forced host) with a mod list will be",
+      "                 used. If no backend servers can be contacted, Velocity will not display any",
+      "                 mod information.",
+      "- \"description\": Uses the description and mod list from the backend server. The first",
+      "                 server in the try (or forced host) list that responds is used for the",
+      "                 description and mod list.",
+      "- \"all\":         Passes everything from the backend server into the response. The Velocity",
+      "                 configuration is used if no servers could be contacted."
   })
   @ConfigKey("ping-passthrough")
   private PingPassthroughMode pingPassthrough = PingPassthroughMode.DISABLED;

proxy/src/main/java/com/velocitypowered/proxy/connection/client/StatusSessionHandler.java

@@ -97,6 +97,24 @@ public class StatusSessionHandler implements MinecraftSessionHandler {
           }
           return fallback;
         });
+      case DESCRIPTION:
+        return pingResponses.thenApply(responses -> {
+          // Find the first non-fallback. If it includes a modlist, add it too.
+          for (ServerPing response : responses) {
+            if (response == fallback) {
+              continue;
+            }
+
+            return new ServerPing(
+                fallback.getVersion(),
+                fallback.getPlayers().orElse(null),
+                response.getDescription(),
+                fallback.getFavicon().orElse(null),
+                response.getModinfo().orElse(null)
+            );
+          }
+          return fallback;
+        });
       default:
         // Not possible, but covered for completeness.
         return CompletableFuture.completedFuture(fallback);