The pom deployed to repo1.maven.org has the project declared like this:
But it is deployed here: http://repo2.maven.org/maven2/org/apache/hadoop/zookeeper/3.3.1
So either the groupId needs to change or the location it is deployed to needs to be changed because having them different results in bad behavior. If you specify the correct groupId in your own pom/ivy files you can't even download zookeeper because it's not where your pom says it is and if you use the "incorrect" groupId then you can download zookeeper but then ivy complains about:
[error] :: problems summary ::
[error] :::: ERRORS
[error] public: bad organisation found in http://repo1.maven.org/maven2/org/apache/hadoop/zookeeper/3.3.1/zookeeper-3.3.1.pom: expected='org.apache.hadoop' found='org.apache.zookeeper'