Triple attachment does not support non-ASCII characters

• I have searched the issues of this repository and believe that this is not a duplicate.

Environment

• Dubbo version: 3.2.5
• Java version: 1.8

Steps to reproduce this issue

1. Insert a value containing non-ASCII characters in the attachment
2. Get the attachment in the provider, where non-ascii characters are converted to "?"

reproduce this issue.

import org.apache.dubbo.rpc.Filter;
import org.apache.dubbo.rpc.Invocation;
import org.apache.dubbo.rpc.Invoker;
import org.apache.dubbo.rpc.Result;
import org.apache.dubbo.rpc.RpcContext;
import org.apache.dubbo.rpc.RpcException;

public class ClientContextAppender implements Filter {
    public ClientContextAppender() {
    }

    public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {
        RpcContext context = RpcContext.getClientAttachment();
        context.setAttachment("non-Ascii", "zh这是中文zh");
        return invoker.invoke(invocation);
    }
}

Expected Behavior

Consistent with the attachment of the dubbo protocol, The triple protocol can also pass values containing non-ASCII characters

Actual Behavior

Non-ASCII characters are converted to '?'

Problem Code

The netty's huffman encoding condition

Not hit netty's huffman encoding condition

When netty does not hit the huffman encoding of the header, it will convert the non-ascii code to '?'

c2b:1857, AsciiString (io.netty.util)
writeAscii:1188, ByteBufUtil (io.netty.buffer)
setCharSequence0:717, AbstractByteBuf (io.netty.buffer)
writeCharSequence:1187, AbstractByteBuf (io.netty.buffer)
encodeStringLiteral:279, HpackEncoder (io.netty.handler.codec.http2)
encodeLiteral:306, HpackEncoder (io.netty.handler.codec.http2)
encodeHeader:194, HpackEncoder (io.netty.handler.codec.http2)
encodeHeadersIgnoreMaxHeaderListSize:145, HpackEncoder (io.netty.handler.codec.http2)
encodeHeadersEnforceMaxHeaderListSize:137, HpackEncoder (io.netty.handler.codec.http2)
encodeHeaders:118, HpackEncoder (io.netty.handler.codec.http2)
encodeHeaders:74, DefaultHttp2HeadersEncoder (io.netty.handler.codec.http2)
...

Hit netty's huffman encoding condition

4.1.86.Final Netty has a bug in the conversion

When netty hits the huffman encoding condition of the header, non-ASCII characters are cleaned to the ASCII range Such a convert may cause unexpected errors Non-ASCII characters may be converted to characters less than 32 For example, envoy will check the value of the header, and if it finds characters less than 32, it will report an error