The project is currently hosted on gitlab.com until migration into Eclipse GitLab is complete:
https://gitlab.com/CodethinkLabs/trustable/trustable
Project documentation is maintained here:
Trustable Software Framework
Gitlab Project Group
You can use the code from these repositories to experiment, test, build, create patches, issue pull requests, etc.
eclipse/tsf - Project group hosted on The Eclipse Foundation's GitLab instance.