Minor code cleanup

proxy/src/main/java/com/velocitypowered/proxy/protocol/ProtocolUtils.java

@@ -271,10 +271,6 @@ public enum ProtocolUtils {
    * @param stringArray the array to write
    */
   public static void writeStringArray(ByteBuf buf, String[] stringArray) {
-    if (stringArray == null) {
-      writeVarInt(buf, 0);
-      return;
-    }
     writeVarInt(buf, stringArray.length);
     for (String s : stringArray) {
       writeString(buf, s);
@@ -292,7 +288,7 @@ public enum ProtocolUtils {
       writeString(buf, property.getName());
       writeString(buf, property.getValue());
       String signature = property.getSignature();
-      if (signature != null) {
+      if (signature != null && !signature.isEmpty()) {
         buf.writeBoolean(true);
         writeString(buf, signature);
       } else {

proxy/src/main/java/com/velocitypowered/proxy/protocol/util/ByteBufDataOutput.java

@@ -10,7 +10,7 @@ import java.io.OutputStream;
 import java.nio.charset.StandardCharsets;
 
 /**
- * A {@link DataOutput} equivalent to {@link ByteBufDataInput}.
+ * A {@link ByteArrayDataOutput} equivalent to {@link ByteBufDataInput}.
  */
 public class ByteBufDataOutput extends OutputStream implements ByteArrayDataOutput {
 

proxy/src/main/java/com/velocitypowered/proxy/util/BrigadierUtils.java

@@ -1,10 +1,8 @@
 package com.velocitypowered.proxy.util;
 
-import com.google.common.base.Preconditions;
 import com.google.common.base.Splitter;
 import com.mojang.brigadier.Command;
 import com.mojang.brigadier.arguments.StringArgumentType;
-import com.mojang.brigadier.builder.ArgumentBuilder;
 import com.mojang.brigadier.builder.LiteralArgumentBuilder;
 import com.mojang.brigadier.builder.RequiredArgumentBuilder;
 import com.mojang.brigadier.context.CommandContext;
@@ -13,7 +11,6 @@ import com.mojang.brigadier.tree.CommandNode;
 import com.mojang.brigadier.tree.LiteralCommandNode;
 import com.velocitypowered.api.command.CommandSource;
 import java.util.Locale;
-import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Provides utilities for working with Brigadier commands.

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

@@ -21,8 +21,7 @@ public class VelocityChannelRegistrar implements ChannelRegistrar {
   public void register(ChannelIdentifier... identifiers) {
     for (ChannelIdentifier identifier : identifiers) {
       Preconditions.checkArgument(identifier instanceof LegacyChannelIdentifier
-              || identifier instanceof MinecraftChannelIdentifier,
+          || identifier instanceof MinecraftChannelIdentifier, "identifier is unknown");
-          "identifier is unknown");
     }
 
     for (ChannelIdentifier identifier : identifiers) {