NPE on Version.getLinearPredecessor() implementation

I get a NullPointerException when I'm trying to get the predecessor of the root version with myVersion.getLinearPredecessor() method.

In the documentation, I should get null. But in the implementation org.apache.jackrabbit.core.version.VersionImpl, I get a NPE if the predecessor is empty (for the node jcr:rootVersion).