In some cases, you might want to extend the plugin with own features. For example, if you have systems available for business that need a very specific integration you could very much use one of the filters or actions to handle such systems yourself.
Currently, the plugin is expanding its features. For example, in a near future the old SOAP interface may be replaced by a newer modern REST API solution. While we are trying to build into that system, this documentation will also cover larger integrations.