Jolt Fixed Constraint Component
The Jolt fixed joint component is the most simple joint type. It links two actors together, such that they move in unison. If all you want is to merge two shapes, you should just attach them to the same actor. The main use case for fixed joints is to make them breakable.
NOTE:
Breakable constraints are currently not implemented in Jolt. That means joints can't automatically break due to physical stress. At the moment you can only make joints break by deactivating a constraint programmatically.