The mapper-murmur3 plugin provides the ability to compute hash of field values at index-time and store them in the index. This can sometimes be helpful when running cardinality aggregations on high-cardinality and large string fields.
Version 7.0.0-alpha1 of the Elastic Stack has not yet been released.
The plugin can be removed with the following command:
sudo bin/elasticsearch-plugin remove mapper-murmur3
The node must be stopped before removing the plugin.