the expression filtering system, that uses an allow-listing mechanism to only accept pre-vetted expressions (through configuration and deployment on the server side). Any unrecognized expression will not the rest of the filtering system is the same. 4.8.2. SCRIPTS AND EXPRESSIONS Apache Unomi allows using different types of expressions in the following subsystems: context.json filters and personalization By default, Apache Unomi comes with some built-in allowed expressions that cover all the internal uses cases. Default allowed MVEL expressions (from https://github.com/apache/unomi/blob/unomi- 1.5.x/