Question of Bookkeeper about "static final String BOOKIE_REGISTRATION_PATH = "/ledgers/available/"

[Dongdong Guo]

I download bookkeeper of  Release 4.0.0 version, than I modify the 
bk_server.conf as blow:

bookiePort=3181
zkLedgersRootPath=/ledger
journalDirectory=/disk1/guodd/bookkeeper/bk-txn
ledgerDirectories=/disk1/guodd/bookkeeper/bk-data
ledgerManagerType=flat
zkLedgersRootPath=/ledger
zkServers=sb052:2181,sb054:2181,sb056:2181
zkTimeout=10000
flushInterval=100

then, I start the bookkeeper using command "bin/bookkeeper bookie", the follow 
exception happened:

Exception in thread "main" java.io.IOException: 
org.apache.zookeeper.KeeperException$NoNodeException: KeeperErrorCode = NoNode 
for /ledgers/available/10.168.2.52:3181
        at org.apache.bookkeeper.bookie.Bookie.registerBookie(Bookie.java:421)
        at org.apache.bookkeeper.bookie.Bookie.<init>(Bookie.java:346)
        at org.apache.bookkeeper.proto.BookieServer.<init>(BookieServer.java:64)
        at org.apache.bookkeeper.proto.BookieServer.main(BookieServer.java:249)
Caused by: org.apache.zookeeper.KeeperException$NoNodeException: 
KeeperErrorCode = NoNode for /ledgers/available/10.168.2.52:3181
        at org.apache.zookeeper.KeeperException.create(KeeperException.java:111)
        at org.apache.zookeeper.KeeperException.create(KeeperException.java:51)
        at org.apache.zookeeper.ZooKeeper.create(ZooKeeper.java:778)
        at org.apache.bookkeeper.bookie.Bookie.registerBookie(Bookie.java:414)
        ... 3 more

I saw the source code, "static final String BOOKIE_REGISTRATION_PATH = 
"/ledgers/available/", user can not configure the BOOKIE_REGISTRATION_PATH , is 
it?, and how do i solve the problem

thanks