Dashbuilder source code can be found on the KIE Tools github repository. Under packages find dashbuilder source. It is a Java project with a maven based build.
There are also repositories for External Components and Reusable Dashboards.
We are acceptting contributions! Send pull requests and our team will review it from github. You can either contribute to the core project or with sample dashboards and external components.
Dashbuilder issues are on the JIRA for the KIE Tools project
World Temperature change chart consuming data from a public JSON service (may take a while to load)