1.0.0+ Extensions to load. 1.0.0+ Extensions to load. 1.0.0+ A set of build extensions to use from this project. 1.0.0+ Describes a build extension to utilise. 1.0.0+ The group ID of the extension's artifact. 1.0.0+ The artifact ID of the extension. 1.0.0+ The version of the extension. 1.1.0+ The class loading strategy: 'self-first' (the default), 'parent-first' (loads classes from the parent, then from the extension) or 'plugin' (follows the rules from extensions defined as plugins).