Fix checksum calculation bug when the payload is a CompositeByteBuf with readerIndex > 0 #1342

Job	Run time
PR Validation	7m 41s
Backward compatibility tests	4s
Bookie Tests	3s
Client Tests	3s
Integration Tests	2s
Compatibility Check Java8	2s
Replication Tests	4s
Build with macos on JDK 11	1s
Compatibility Check Java11	5s
Remaining Tests	3s
Compatibility Check Java17	3s
Build with windows on JDK 11	2s
TLS Tests	3s
StreamStorage Tests	2s
OWASP Dependency Check	0s
Shell tests	3s
	8m 21s

Provide feedback