In cedacc8#diff-7b481e6af9ca6e4b2759e2f498434346fd0882918f80c6adc2a95538cd33b6ebR585 the logic was changed how the message is send. This introduces a ClassCastException when using something like this: ...

WARN [org.apache.zookeeper.ClientCnxn] - Session 0x0 for server null, unexpected error, closing socket connection and attempting reconnect java.lang.ClassCastException: class ...

Using generics results in more robust code and avoids ClassCastExceptions in your Java programs. This in-depth tutorial introduces you to generics and their types and methods.