Fix the completionObjects leak problem. (#4285) #2313

Job	Run time
PR Validation	7m 59s
Integration Tests	3m 26s
Build with windows on JDK 11	6m 1s
Build with macos on JDK 11	2m 41s
Bookie Tests	6m 16s
Client Tests	6m 18s
Backward compatibility tests	3m 42s
Compatibility Check Java8	6m 20s
Replication Tests	6m 18s
Compatibility Check Java11	6m 19s
Remaining Tests	6m 19s
Compatibility Check Java17	6m 21s
TLS Tests	6m 19s
OWASP Dependency Check	0s
StreamStorage Tests	6m 19s
Shell tests	33s
	1h 21m 11s

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