Unit test stalling

When guava dependency is upgraded from 14.0.1 to the latest version (26.0-jre/25.0-jre), some unit test stall indefinitely and testing never finishes up.

For example, here HdfsNNFailoverTest stall indefinitely. Log excerpts for unit test run with guava 25.0-jre:

13:54:39.392 [QUIET] [system.out]    [junit4] HEARTBEAT J0 PID(258@8471261c0ae9): 2018-10-12T13:54:39, stalled for 70.6s at: HdfsNNFailoverTest (suite)

13:55:39.394 [QUIET] [system.out]    [junit4] HEARTBEAT J0 PID(258@8471261c0ae9): 2018-10-12T13:55:39, stalled for  131s at: HdfsNNFailoverTest (suite)

13:56:39.395 [QUIET] [system.out]    [junit4] HEARTBEAT J0 PID(258@8471261c0ae9): 2018-10-12T13:56:39, stalled for  191s at: HdfsNNFailoverTest (suite)

13:57:39.396 [QUIET] [system.out]    [junit4] HEARTBEAT J0 PID(258@8471261c0ae9): 2018-10-12T13:57:39, stalled for  251s at: HdfsNNFailoverTest (suite)

13:58:39.398 [QUIET] [system.out]    [junit4] HEARTBEAT J0 PID(258@8471261c0ae9): 2018-10-12T13:58:39, stalled for  311s at: HdfsNNFailoverTest (suite)

13:59:39.399 [QUIET] [system.out]    [junit4] HEARTBEAT J0 PID(258@8471261c0ae9): 2018-10-12T13:59:39, stalled for  371s at: HdfsNNFailoverTest (suite)

Note: guava upgrade from default version 14.0.1 to 25.0-jre or 26.0-jre requires solr code changes. The diff file (sole-release.diff) is attached with this bug.