bump java etcd client to 0.0.21 (#5309)
bump java etcd client to 0.0.21 (#5309)

Co-authored-by: Brendan Doyle <e9401a09b1612f6a181940f70779b7a4ece5c52c@qualtrics.com>
style95/openwhisk,style95/openwhisk,style95/openwhisk,style95/openwhisk,style95/openwhisk,style95/openwhisk,style95/openwhisk