private void unschedule(String definitionName, ScheduledFuture<?> scheduledFuture) {

    m_futureMap.remove(definitionName);

    if (null != scheduledFuture) {
      scheduledFuture.cancel(true);
      LOG.info("Unscheduled server alert {}", definitionName);
    }
  }
Invokes {@link ScheduledFuture#cancel(boolean)} and removes the mapping
from {@link #m_futureMap}. Does nothing if the future is not scheduled.

@param scheduledFuture
ambari-server/src/main/java/org/apache/ambari/server/state/services/AmbariServerAlertService.java