public static boolean removeConnectionManager(HttpClientConnectionManager connectionManager) {
        boolean wasRemoved = connectionManagers.remove(connectionManager) != null;
        if (connectionManagers.isEmpty()) {
            shutdown();
        }
        return wasRemoved;
    }
Removes the given connection manager from this reaper,
and shutting down the reaper if there is zero connection manager left.

@return true if the connection manager has been successfully removed;
false otherwise.
aws-java-sdk-core/src/main/java/com/amazonaws/http/IdleConnectionReaper.java