I was using ZooKeeper client in WebSphere Liberty and attempting to configure SSL/TLS for client connections.
To do so, I must add the system property zookeeper.client.secure=true. In WebSphere Liberty, java system properties are placed in a file called bootstrap.properties - each property on a separate line. I accidentally added a space at the end of the line. When ZKConfig.getBoolean() attempted to convert this string to a boolean, it returned false due to the space at the end.
ZKConfig.getBoolean() should trim the string before attempting to convert to a boolean.