## What changed?
Keep the total number and the size of the external payloads per the
workflow execution
## Why?
We are working on building the support for external payloads in SDK,
which are stored outside of Temporal. We'd like to be able to show the
total size and the number of external payloads in the given workflow
execution.
## How did you test it?
- [ ] built
- [X] run locally and tested manually
- [ ] covered by existing tests
- [X] added new unit test(s)
- [x] added new functional test(s)
## Potential risks
N/A
