Seeing many elastic established connections even after call close

Connections getting established event after call Client.close() in elastic search

We use latest Elastic search version.

java 3608 ubuntu 494u IPv6 25325750 0t0 TCP ip-XXX-XX-XX-XXX.ap-southeast-1.compute.internal:53562->ec2-XX-XXX-XXX-XXX.ap-southeast-1.compute.amazonaws.com:9300 (ESTABLISHED)
java 3608 ubuntu 495u IPv6 25325751 0t0 TCP ip-XXX-XX-XX-XXX.ap-southeast-1.compute.internal:53563->ec2-XX-XXX-XXX-XXX.ap-southeast-1.compute.amazonaws.com:9300 (ESTABLISHED)
java 3608 ubuntu 496u IPv6 25325752 0t0 TCP ip-XXX-XX-XX-XXX.ap-southeast-1.compute.internal:53564->ec2-XX-XXX-XXX-XXX.ap-southeast-1.compute.amazonaws.com:9300 (ESTABLISHED)
java 3608 ubuntu 497u IPv6 25325753 0t0 TCP ip-XXX-XX-XX-XXX.ap-southeast-1.compute.internal:53565->ec2-XX-XXX-XXX-XXX.ap-southeast-1.compute.amazonaws.com:9300 (ESTABLISHED)
java 3608 ubuntu 498u IPv6 25325754 0t0 TCP ip-XXX-XX-XX-XXX.ap-southeast-1.compute.internal:53566->ec2-XX-XXX-XXX-XXX.ap-southeast-1.compute.amazonaws.com:9300 (ESTABLISHED)
java 3608 ubuntu 499u IPv6 25325755 0t0 TCP ip-XXX-XX-XX-XXX.ap-southeast-1.compute.internal:53567->ec2-XX-XXX-XXX-XXX.ap-southeast-1.compute.amazonaws.com:9300 (ESTABLISHED)
java 3608 ubuntu 500u IPv6 25325756 0t0 TCP ip-XXX-XX-XX-XXX.ap-southeast-1.compute.internal:53568->ec2-XX-XXX-XXX-XXX.ap-southeast-1.compute.amazonaws.com:9300 (ESTABLISHED)
java 3608 ubuntu 501u IPv6 25325757 0t0 TCP ip-XXX-XX-XX-XXX.ap-southeast-1.compute.internal:53569->ec2-XX-XXX-XXX-XXX.ap-southeast-1.compute.amazonaws.com:9300 (ESTABLISHED)
java 3608 ubuntu 502u IPv6 25325758 0t0 TCP ip-XXX-XX-XX-XXX.ap-southeast-1.compute.internal:53570->ec2-XX-XXX-XXX-XXX.ap-southeast-1.compute.amazonaws.com:9300 (ESTABLISHED)
java 3608 ubuntu 503u IPv6 25325759 0t0 TCP ip-XXX-XX-XX-XXX.ap-southeast-1.compute.internal:53571->ec2-XX-XXX-XXX-XXX.ap-southeast-1.compute.amazonaws.com:9300 (ESTABLISHED)
java 3608 ubuntu 504u IPv6 25325760 0t0 TCP ip-XXX-XX-XX-XXX.ap-southeast-1.compute.internal:53572->ec2-XX-XXX-XXX-XXX.ap-southeast-1.compute.amazonaws.com:9300 (ESTABLISHED)
java 3608 ubuntu 505u IPv6 25325761 0t0 TCP ip-XXX-XX-XX-XXX.ap-southeast-1.compute.internal:53573->ec2-XX-XXX-XXX-XXX.ap-southeast-1.compute.amazonaws.com:9300 (ESTABLISHED)
java 3608 ubuntu 506u IPv6 25325762 0t0 TCP ip-XXX-XX-XX-XXX.ap-southeast-1.compute.internal:53574->ec2-XX-XXX-XXX-XXX.ap-southeast-1.compute.amazonaws.com:9300 (ESTABLISHED)
java 3608 ubuntu 507u IPv6 25325763 0t0 TCP ip-XXX-XX-XX-XXX.ap-southeast-1.compute.internal:53575->ec2-XX-XXX-XXX-XXX.ap-southeast-1.compute.amazonaws.com:9300 (ESTABLISHED)