Fix checksum calculation bug when the payload is a CompositeByteBuf with readerIndex > 0 #1349

Job	Run time
PR Validation	7m 46s
Integration Tests	7m 4s
Build with macos on JDK 11	6m 46s
Compatibility Check Java8	19m 31s
Backward compatibility tests	3m 37s
Compatibility Check Java11	20m 3s
Compatibility Check Java17	19m 19s
OWASP Dependency Check	0s
Bookie Tests	18m 50s
Build with windows on JDK 11	6m 56s
Client Tests	38m 33s
Replication Tests	23m 51s
Remaining Tests	17m 54s
TLS Tests	12m 58s
StreamStorage Tests	18m 51s
Shell tests	31s
	3h 42m 30s

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