Convert Velocity to use ByteBuf-derived plugin message packets

Only tested with 1.12.2, not 1.13 or Forge

proxy/src/main/java/com/velocitypowered/proxy/Velocity.java

@@ -1,5 +1,7 @@
 package com.velocitypowered.proxy;
 
+import io.netty.util.ResourceLeakDetector;
+import io.netty.util.ResourceLeakDetector.Level;
 import java.text.DecimalFormat;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -35,6 +37,8 @@ public class Velocity {
       return;
     }
 
+    ResourceLeakDetector.setLevel(Level.PARANOID);
+
     long startTime = System.currentTimeMillis();
 
     VelocityServer server = new VelocityServer(options);

proxy/src/main/java/com/velocitypowered/proxy/connection/MinecraftConnection.java

@@ -131,8 +131,8 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
         try {
           sessionHandler.exception(cause);
         } catch (Exception ex) {
-          logger.error("{}: exception handling exception", (association != null ? association :
-              channel.remoteAddress()), cause);
+          logger.error("{}: exception handling exception in {}",
+              (association != null ? association : channel.remoteAddress()), sessionHandler, cause);
         }
       }
 
@@ -140,7 +140,7 @@ public class MinecraftConnection extends ChannelInboundHandlerAdapter {
         if (cause instanceof ReadTimeoutException) {
           logger.error("{}: read timed out", association);
         } else {
-          logger.error("{}: exception encountered", association, cause);
+          logger.error("{}: exception encountered in {}", association, sessionHandler, cause);
         }
       }
 

proxy/src/main/java/com/velocitypowered/proxy/connection/backend/BackendPlaySessionHandler.java

@@ -25,6 +25,8 @@ import com.velocitypowered.proxy.protocol.packet.PluginMessage;
 import com.velocitypowered.proxy.protocol.packet.TabCompleteResponse;
 import com.velocitypowered.proxy.protocol.util.PluginMessageUtil;
 import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufUtil;
+import io.netty.buffer.Unpooled;
 
 public class BackendPlaySessionHandler implements MinecraftSessionHandler {
 
@@ -119,12 +121,15 @@ public class BackendPlaySessionHandler implements MinecraftSessionHandler {
       return false;
     }
 
+    byte[] copy = ByteBufUtil.getBytes(packet.content());
     PluginMessageEvent event = new PluginMessageEvent(serverConn, serverConn.getPlayer(), id,
-        packet.getData());
+        copy);
     server.getEventManager().fire(event)
         .thenAcceptAsync(pme -> {
           if (pme.getResult().isAllowed() && !playerConnection.isClosed()) {
-            playerConnection.write(packet);
+            PluginMessage copied = new PluginMessage(packet.getChannel(),
+                Unpooled.wrappedBuffer(copy));
+            playerConnection.write(copied);
           }
         }, playerConnection.eventLoop());
     return true;
@@ -163,6 +168,9 @@ public class BackendPlaySessionHandler implements MinecraftSessionHandler {
 
   @Override
   public void handleGeneric(MinecraftPacket packet) {
+    if (packet instanceof PluginMessage) {
+      ((PluginMessage) packet).retain();
+    }
     playerConnection.write(packet);
   }
 

proxy/src/main/java/com/velocitypowered/proxy/connection/backend/VelocityServerConnection.java

@@ -33,6 +33,7 @@ import com.velocitypowered.proxy.protocol.packet.Handshake;
 import com.velocitypowered.proxy.protocol.packet.PluginMessage;
 import com.velocitypowered.proxy.protocol.packet.ServerLogin;
 import com.velocitypowered.proxy.server.VelocityRegisteredServer;
+import io.netty.buffer.Unpooled;
 import io.netty.channel.Channel;
 import io.netty.channel.ChannelFutureListener;
 import io.netty.channel.ChannelInitializer;
@@ -212,9 +213,7 @@ public class VelocityServerConnection implements MinecraftConnectionAssociation,
 
     MinecraftConnection mc = ensureConnected();
 
-    PluginMessage message = new PluginMessage();
-    message.setChannel(identifier.getId());
-    message.setData(data);
+    PluginMessage message = new PluginMessage(identifier.getId(), Unpooled.wrappedBuffer(data));
     mc.write(message);
     return true;
   }

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

@@ -29,6 +29,9 @@ import com.velocitypowered.proxy.protocol.packet.TabCompleteResponse.Offer;
 import com.velocitypowered.proxy.protocol.packet.TitlePacket;
 import com.velocitypowered.proxy.protocol.util.PluginMessageUtil;
 import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufUtil;
+import io.netty.buffer.Unpooled;
+import io.netty.util.ReferenceCountUtil;
 import java.util.ArrayDeque;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -80,6 +83,13 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
     }
   }
 
+  @Override
+  public void deactivated() {
+    for (PluginMessage message : loginPluginMessages) {
+      ReferenceCountUtil.release(message);
+    }
+  }
+
   @Override
   public boolean handle(KeepAlive packet) {
     VelocityServerConnection serverConnection = player.getConnectedServer();
@@ -213,10 +223,10 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
             + "ready. Channel: {}. Packet discarded.", packet.getChannel());
       } else if (PluginMessageUtil.isRegister(packet)) {
         player.getKnownChannels().addAll(PluginMessageUtil.getChannels(packet));
-        backendConn.write(packet);
+        backendConn.write(packet.retain());
       } else if (PluginMessageUtil.isUnregister(packet)) {
         player.getKnownChannels().removeAll(PluginMessageUtil.getChannels(packet));
-        backendConn.write(packet);
+        backendConn.write(packet.retain());
       } else if (PluginMessageUtil.isMcBrand(packet)) {
         backendConn.write(PluginMessageUtil.rewriteMinecraftBrand(packet, server.getVersion()));
       } else {
@@ -236,16 +246,23 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
             // but further aggravated by Velocity. To work around these issues, we will queue any
             // non-FML handshake messages to be sent once the FML handshake has completed or the
             // JoinGame packet has been received by the proxy, whichever comes first.
-            loginPluginMessages.add(packet);
+            //
+            // We also need to make sure to retain these packets so they can be flushed
+            // appropriately.
+            loginPluginMessages.add(packet.retain());
           } else {
             ChannelIdentifier id = server.getChannelRegistrar().getFromId(packet.getChannel());
             if (id == null) {
-              backendConn.write(packet);
+              backendConn.write(packet.retain());
             } else {
+              byte[] copy = ByteBufUtil.getBytes(packet.content());
               PluginMessageEvent event = new PluginMessageEvent(player, serverConn, id,
-                  packet.getData());
-              server.getEventManager().fire(event).thenAcceptAsync(pme -> backendConn.write(packet),
-                  backendConn.eventLoop());
+                  ByteBufUtil.getBytes(packet.content()));
+              server.getEventManager().fire(event).thenAcceptAsync(pme -> {
+                PluginMessage message = new PluginMessage(packet.getChannel(),
+                    Unpooled.wrappedBuffer(copy));
+                backendConn.write(message);
+              }, backendConn.eventLoop());
             }
           }
         }
@@ -272,6 +289,9 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
 
     MinecraftConnection smc = serverConnection.getConnection();
     if (smc != null && serverConnection.getPhase().consideredComplete()) {
+      if (packet instanceof PluginMessage) {
+        ((PluginMessage) packet).retain();
+      }
       smc.write(packet);
     }
   }

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

@@ -49,6 +49,7 @@ import com.velocitypowered.proxy.tablist.VelocityTabList;
 import com.velocitypowered.proxy.util.VelocityMessages;
 import com.velocitypowered.proxy.util.collect.CappedSet;
 import io.netty.buffer.ByteBufUtil;
+import io.netty.buffer.Unpooled;
 import java.net.InetSocketAddress;
 import java.util.Collection;
 import java.util.Collections;
@@ -570,9 +571,7 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
   public boolean sendPluginMessage(ChannelIdentifier identifier, byte[] data) {
     Preconditions.checkNotNull(identifier, "identifier");
     Preconditions.checkNotNull(data, "data");
-    PluginMessage message = new PluginMessage();
-    message.setChannel(identifier.getId());
-    message.setData(data);
+    PluginMessage message = new PluginMessage(identifier.getId(), Unpooled.wrappedBuffer(data));
     minecraftConnection.write(message);
     return true;
   }

proxy/src/main/java/com/velocitypowered/proxy/connection/forge/legacy/LegacyForgeHandshakeBackendPhase.java

@@ -114,7 +114,7 @@ public enum LegacyForgeHandshakeBackendPhase implements BackendConnectionPhase {
       serverConnection.setConnectionPhase(newPhase);
 
       // Write the packet to the player, we don't need it now.
-      player.getMinecraftConnection().write(message);
+      player.getMinecraftConnection().write(message.retain());
       return true;
     }
 

proxy/src/main/java/com/velocitypowered/proxy/connection/forge/legacy/LegacyForgeHandshakeClientPhase.java

@@ -212,7 +212,7 @@ public enum LegacyForgeHandshakeClientPhase implements ClientConnectionPhase {
       PluginMessage message,
       MinecraftConnection backendConn) {
     // Send the packet on to the server.
-    backendConn.write(message);
+    backendConn.write(message.retain());
 
     // We handled the packet. No need to continue processing.
     return true;

proxy/src/main/java/com/velocitypowered/proxy/connection/forge/legacy/LegacyForgeUtil.java

@@ -27,9 +27,8 @@ class LegacyForgeUtil {
    */
   static byte getHandshakePacketDiscriminator(PluginMessage message) {
     Preconditions.checkArgument(message.getChannel().equals(FORGE_LEGACY_HANDSHAKE_CHANNEL));
-    byte[] data = message.getData();
-    Preconditions.checkArgument(data.length >= 1);
-    return data[0];
+    Preconditions.checkArgument(message.content().isReadable());
+    return message.content().getByte(0);
   }
 
   /**
@@ -44,7 +43,7 @@ class LegacyForgeUtil {
         .checkArgument(message.getChannel().equals(FORGE_LEGACY_HANDSHAKE_CHANNEL),
             "message is not a FML HS plugin message");
 
-    ByteBuf byteBuf = Unpooled.wrappedBuffer(message.getData());
+    ByteBuf byteBuf = message.content().retainedSlice();
     try {
       byte discriminator = byteBuf.readByte();
 
@@ -75,7 +74,7 @@ class LegacyForgeUtil {
   static PluginMessage resetPacket() {
     PluginMessage msg = new PluginMessage();
     msg.setChannel(FORGE_LEGACY_HANDSHAKE_CHANNEL);
-    msg.setData(FORGE_LEGACY_HANDSHAKE_RESET_DATA.clone());
+    msg.replace(Unpooled.wrappedBuffer(FORGE_LEGACY_HANDSHAKE_RESET_DATA.clone()));
     return msg;
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/LoginPluginMessage.java

@@ -4,24 +4,24 @@ import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
+import com.velocitypowered.proxy.protocol.util.DeferredByteBufHolder;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
-public class LoginPluginMessage implements MinecraftPacket {
+public class LoginPluginMessage extends DeferredByteBufHolder implements MinecraftPacket {
 
   private int id;
   private @Nullable String channel;
-  private ByteBuf data = Unpooled.EMPTY_BUFFER;
 
   public LoginPluginMessage() {
-
+    super(null);
   }
 
   public LoginPluginMessage(int id, @Nullable String channel, ByteBuf data) {
+    super(data);
     this.id = id;
     this.channel = channel;
-    this.data = data;
   }
 
   public int getId() {
@@ -35,16 +35,12 @@ public class LoginPluginMessage implements MinecraftPacket {
     return channel;
   }
 
-  public ByteBuf getData() {
-    return data;
-  }
-
   @Override
   public String toString() {
     return "LoginPluginMessage{"
         + "id=" + id
         + ", channel='" + channel + '\''
-        + ", data=" + data
+        + ", data=" + super.toString()
         + '}';
   }
 
@@ -53,9 +49,9 @@ public class LoginPluginMessage implements MinecraftPacket {
     this.id = ProtocolUtils.readVarInt(buf);
     this.channel = ProtocolUtils.readString(buf);
     if (buf.isReadable()) {
-      this.data = buf.readSlice(buf.readableBytes());
+      this.replace(buf.readSlice(buf.readableBytes()));
     } else {
-      this.data = Unpooled.EMPTY_BUFFER;
+      this.replace(Unpooled.EMPTY_BUFFER);
     }
   }
 
@@ -66,7 +62,7 @@ public class LoginPluginMessage implements MinecraftPacket {
       throw new IllegalStateException("Channel is not specified!");
     }
     ProtocolUtils.writeString(buf, channel);
-    buf.writeBytes(data);
+    buf.writeBytes(content());
   }
 
   @Override

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/PluginMessage.java

@@ -1,21 +1,29 @@
 package com.velocitypowered.proxy.protocol.packet;
 
-import static com.velocitypowered.proxy.connection.VelocityConstants.EMPTY_BYTE_ARRAY;
 import static com.velocitypowered.proxy.protocol.util.PluginMessageUtil.transformLegacyToModernChannel;
 
 import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
-import com.velocitypowered.proxy.protocol.util.PluginMessageUtil;
+import com.velocitypowered.proxy.protocol.util.DeferredByteBufHolder;
 import io.netty.buffer.ByteBuf;
-import io.netty.buffer.ByteBufUtil;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
-public class PluginMessage implements MinecraftPacket {
+public class PluginMessage extends DeferredByteBufHolder implements MinecraftPacket {
 
   private @Nullable String channel;
-  private byte[] data = EMPTY_BYTE_ARRAY;
+
+  public PluginMessage() {
+    super(null);
+  }
+
+  public PluginMessage(String channel,
+      @MonotonicNonNull ByteBuf backing) {
+    super(backing);
+    this.channel = channel;
+  }
 
   public String getChannel() {
     if (channel == null) {
@@ -28,19 +36,11 @@ public class PluginMessage implements MinecraftPacket {
     this.channel = channel;
   }
 
-  public byte[] getData() {
-    return data;
-  }
-
-  public void setData(byte[] data) {
-    this.data = data;
-  }
-
   @Override
   public String toString() {
     return "PluginMessage{"
         + "channel='" + channel + '\''
-        + ", data=<removed>"
+        + ", data=" + super.toString()
         + '}';
   }
 
@@ -50,8 +50,7 @@ public class PluginMessage implements MinecraftPacket {
     if (version.compareTo(ProtocolVersion.MINECRAFT_1_13) >= 0) {
       this.channel = transformLegacyToModernChannel(this.channel);
     }
-    this.data = new byte[buf.readableBytes()];
-    buf.readBytes(data);
+    this.replace(buf.readRetainedSlice(buf.readableBytes()));
   }
 
   @Override
@@ -64,11 +63,51 @@ public class PluginMessage implements MinecraftPacket {
     } else {
       ProtocolUtils.writeString(buf, this.channel);
     }
-    buf.writeBytes(data);
+    buf.writeBytes(content());
   }
 
   @Override
   public boolean handle(MinecraftSessionHandler handler) {
     return handler.handle(this);
   }
+
+  @Override
+  public PluginMessage copy() {
+    return (PluginMessage) super.copy();
+  }
+
+  @Override
+  public PluginMessage duplicate() {
+    return (PluginMessage) super.duplicate();
+  }
+
+  @Override
+  public PluginMessage retainedDuplicate() {
+    return (PluginMessage) super.retainedDuplicate();
+  }
+
+  @Override
+  public PluginMessage replace(ByteBuf content) {
+    return (PluginMessage) super.replace(content);
+  }
+
+  @Override
+  public PluginMessage retain() {
+    return (PluginMessage) super.retain();
+  }
+
+  @Override
+  public PluginMessage retain(int increment) {
+    return (PluginMessage) super.retain(increment);
+  }
+
+  @Override
+  public PluginMessage touch() {
+    return (PluginMessage) super.touch();
+  }
+
+  @Override
+  public PluginMessage touch(Object hint) {
+    return (PluginMessage) super.touch(hint);
+  }
 }

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

@@ -0,0 +1,136 @@
+package com.velocitypowered.proxy.protocol.util;
+
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufHolder;
+import io.netty.util.IllegalReferenceCountException;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
+
+/**
+ * A special-purpose implementation of {@code ByteBufHolder} that can defer accepting its buffer.
+ * This is required because Velocity packets are, for better or worse, mutable.
+ */
+public class DeferredByteBufHolder implements ByteBufHolder {
+
+  @MonotonicNonNull
+  private ByteBuf backing;
+
+  public DeferredByteBufHolder(
+      @MonotonicNonNull ByteBuf backing) {
+    this.backing = backing;
+  }
+
+  @Override
+  public ByteBuf content() {
+    if (backing == null) {
+      throw new IllegalStateException("Trying to obtain contents of holder with a null buffer");
+    }
+    if (backing.refCnt() <= 0) {
+      throw new IllegalReferenceCountException(backing.refCnt());
+    }
+    return backing;
+  }
+
+  @Override
+  public ByteBufHolder copy() {
+    if (backing == null) {
+      throw new IllegalStateException("Trying to obtain contents of holder with a null buffer");
+    }
+    return new DeferredByteBufHolder(backing.copy());
+  }
+
+  @Override
+  public ByteBufHolder duplicate() {
+    if (backing == null) {
+      throw new IllegalStateException("Trying to obtain contents of holder with a null buffer");
+    }
+    return new DeferredByteBufHolder(backing.duplicate());
+  }
+
+  @Override
+  public ByteBufHolder retainedDuplicate() {
+    if (backing == null) {
+      throw new IllegalStateException("Trying to obtain contents of holder with a null buffer");
+    }
+    return new DeferredByteBufHolder(backing.retainedDuplicate());
+  }
+
+  @Override
+  public ByteBufHolder replace(ByteBuf content) {
+    if (content == null) {
+      throw new NullPointerException("content");
+    }
+    this.backing = content;
+    return this;
+  }
+
+  @Override
+  public int refCnt() {
+    if (backing == null) {
+      throw new IllegalStateException("Trying to obtain contents of holder with a null buffer");
+    }
+    return backing.refCnt();
+  }
+
+  @Override
+  public ByteBufHolder retain() {
+    if (backing == null) {
+      throw new IllegalStateException("Trying to obtain contents of holder with a null buffer");
+    }
+    backing.retain();
+    return this;
+  }
+
+  @Override
+  public ByteBufHolder retain(int increment) {
+    if (backing == null) {
+      throw new IllegalStateException("Trying to obtain contents of holder with a null buffer");
+    }
+    backing.retain(increment);
+    return this;
+  }
+
+  @Override
+  public ByteBufHolder touch() {
+    if (backing == null) {
+      throw new IllegalStateException("Trying to obtain contents of holder with a null buffer");
+    }
+    backing.touch();
+    return this;
+  }
+
+  @Override
+  public ByteBufHolder touch(Object hint) {
+    if (backing == null) {
+      throw new IllegalStateException("Trying to obtain contents of holder with a null buffer");
+    }
+    backing.touch(hint);
+    return this;
+  }
+
+  @Override
+  public boolean release() {
+    if (backing == null) {
+      throw new IllegalStateException("Trying to obtain contents of holder with a null buffer");
+    }
+    return backing.release();
+  }
+
+  @Override
+  public boolean release(int decrement) {
+    if (backing == null) {
+      throw new IllegalStateException("Trying to obtain contents of holder with a null buffer");
+    }
+    return backing.release(decrement);
+  }
+
+  @Override
+  public String toString() {
+    String str = "DeferredByteBufHolder[";
+    if (backing == null) {
+      str += "null";
+    } else {
+      str += backing.toString();
+    }
+    return str + "]";
+  }
+}

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

@@ -11,7 +11,9 @@ import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import com.velocitypowered.proxy.protocol.packet.PluginMessage;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
+import io.netty.util.ByteProcessor;
 import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 import java.util.Locale;
@@ -93,12 +95,12 @@ public class PluginMessageUtil {
     checkNotNull(message, "message");
     checkArgument(isRegister(message) || isUnregister(message), "Unknown channel type %s",
             message.getChannel());
-    if (message.getData().length == 0) {
+    if (!message.content().isReadable()) {
       // If we try to split this, we will get an one-element array with the empty string, which
       // has caused issues with 1.13+ compatibility. Just return an empty list.
       return ImmutableList.of();
     }
-    String channels = new String(message.getData(), StandardCharsets.UTF_8);
+    String channels = message.content().toString(StandardCharsets.UTF_8);
     return ImmutableList.copyOf(channels.split("\0"));
   }
 
@@ -114,10 +116,9 @@ public class PluginMessageUtil {
     Preconditions.checkArgument(channels.size() > 0, "no channels specified");
     String channelName = protocolVersion.compareTo(ProtocolVersion.MINECRAFT_1_13) >= 0
         ? REGISTER_CHANNEL : REGISTER_CHANNEL_LEGACY;
-    PluginMessage message = new PluginMessage();
-    message.setChannel(channelName);
-    message.setData(String.join("\0", channels).getBytes(StandardCharsets.UTF_8));
-    return message;
+    ByteBuf contents = Unpooled.buffer();
+    contents.writeCharSequence(String.join("\0", channels), StandardCharsets.UTF_8);
+    return new PluginMessage(channelName, contents);
   }
 
   /**
@@ -133,21 +134,11 @@ public class PluginMessageUtil {
 
     String toAppend = " (" + version.getName() + ")";
 
-    byte[] rewrittenData;
     ByteBuf rewrittenBuf = Unpooled.buffer();
-    try {
-      String currentBrand = ProtocolUtils.readString(Unpooled.wrappedBuffer(message.getData()));
-      ProtocolUtils.writeString(rewrittenBuf, currentBrand + toAppend);
-      rewrittenData = new byte[rewrittenBuf.readableBytes()];
-      rewrittenBuf.readBytes(rewrittenData);
-    } finally {
-      rewrittenBuf.release();
-    }
+    String currentBrand = ProtocolUtils.readString(message.content().slice());
+    ProtocolUtils.writeString(rewrittenBuf, currentBrand + toAppend);
 
-    PluginMessage newMsg = new PluginMessage();
-    newMsg.setChannel(message.getChannel());
-    newMsg.setData(rewrittenData);
-    return newMsg;
+    return new PluginMessage(message.getChannel(), rewrittenBuf);
   }
 
   private static final Pattern INVALID_IDENTIFIER_REGEX = Pattern.compile("[^a-z0-9\\-_]*");
@@ -185,5 +176,4 @@ public class PluginMessageUtil {
         return "legacy:" + INVALID_IDENTIFIER_REGEX.matcher(lower).replaceAll("");
     }
   }
-
 }