Remove potentially high-frequency usages of streams

proxy/src/main/java/com/velocitypowered/proxy/command/VelocityCommandManager.java

@@ -68,11 +68,14 @@ public class VelocityCommandManager implements CommandManager {
 
         String alias = split[0];
         if (split.length == 1) {
-            return Optional.of(commands.entrySet().stream()
-                    .filter(ent -> ent.getKey().regionMatches(true, 0, alias, 0, alias.length()))
-                    .filter(ent -> ent.getValue().hasPermission(source, new String[0]))
-                    .map(ent -> "/" + ent.getKey())
-                    .collect(Collectors.toList()));
+            List<String> availableCommands = new ArrayList<>();
+            for (Map.Entry<String, Command> entry : commands.entrySet()) {
+                if (entry.getKey().regionMatches(true, 0, alias, 0, alias.length()) &&
+                        entry.getValue().hasPermission(source, new String[0])) {
+                    availableCommands.add("/" + entry.getKey());
+                }
+            }
+            return Optional.of(availableCommands);
         }
 
         String[] actualArgs = Arrays.copyOfRange(split, 1, split.length);

proxy/src/main/java/com/velocitypowered/proxy/messages/VelocityChannelRegistrar.java

@@ -7,6 +7,7 @@ import com.velocitypowered.api.proxy.messages.ChannelRegistrar;
 import com.velocitypowered.api.proxy.messages.LegacyChannelIdentifier;
 import com.velocitypowered.api.proxy.messages.MinecraftChannelIdentifier;
 
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
@@ -44,10 +45,11 @@ public class VelocityChannelRegistrar implements ChannelRegistrar {
     }
 
     public Collection<String> getModernChannelIds() {
-        return identifierMap.values().stream()
-                .filter(i -> i instanceof MinecraftChannelIdentifier)
-                .map(ChannelIdentifier::getId)
-                .collect(Collectors.toList());
+        Collection<String> ids = new ArrayList<>();
+        for (ChannelIdentifier value : identifierMap.values()) {
+            ids.add(value.getId());
+        }
+        return ids;
     }
 
     public boolean registered(String id) {