Expected behavior

No char[] allocation when logger disabled

Actual behavior

The logger always performing a hex dump of the ByteBufs regarless whether or not the log would take place. I faced with huge allocation during run grpc benchmarks

Netty version

io.netty:netty-codec-http2:4.1.13.Final

JVM version (e.g. java -version)

java version "1.8.0_131"
Java(TM) SE Runtime Environment (build 1.8.0_131-b11)
Java HotSpot(TM) 64-Bit Server VM (build 25.131-b11, mixed mode)