This is the Chatter module created by Appronto. It's completely free. It's mostly Java and Javascript based. In the /Module folder the Mendix module is included which can be imported in Mendix 7.2 and up. The /Widget folder contains the source of the widget and a release MPK file. 

Please follow the installation instructions from the Mendix app store. If you're updating please check the documentation again for recommended values for the constants.