[HBASE-11187] Fix TableServers for jdk7

Author: manukranthk

Summary: TableServers was using a jdk8 feature.  Since we still build on jdk7 this diff fixes the issue

Test Plan: git co fix_table_servers  && mvn clean test -Dtest=TestLoadShedding

Reviewers: rshroff, daviddeng, aaiyer, elliott

Reviewed By: daviddeng

Subscribers: manukranthk, elliot, daviddeng, adela

Differential Revision: https://phabricator.fb.com/D1333896

git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.89-fb@1595524 13f79535-47bb-0310-9956-ffa450edef68