Why? The python-weka-wrapper project has a wrapper for the MultiSearch meta-classifier. But in order to use the metrics, it requires access to an array of weka.core.Tag objects that represent all the available metrics. However, the multi-search project no longer has a static field for these metrics, but uses an internal factory for that. This change occurred to make it also usable by other frameworks, like MEKA. Hence a new release was required that exposed these dynamic tags via a public method.