[Issue-434] Update the copyright year to 2021 (#454)
[Issue-434] Update the copyright year to 2021 (#454)

Signed-off-by: Charlie <4ad90d5f6d00e3e6a759671f9cf7388f6761245d@dell.com>

Co-authored-by: Brian Zhou <3a1be532a17fd34bf07b5f202b2f60565a486979@emc.com>
pravega/flink-connectors,pravega/flink-connectors