Epic Design Hypothesis: 250 character limitation in API but unlimited in User Interface

Issue Summary

In Epic Details panel> Design> Hypothesis,

The textbox allows in user interface a large amount of character for this field. 

^{Ex: I was able to add a text as big as 50K Character}

However, the API enforces a limit of 250 character for the same field
Note: The API will display any text over 250 character that was set in the UI instead!

Steps to Reproduce

1. Open an Epic, and go to the Hypothesis field under Design
2. Add a text larger than 250 from the UI
3. See the text is saved as expected.
4. Try from the API to do the same
   ex:

[
  {
     "op": "replace",
     "path": "/hypothesis",
     "value": "Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Aenean commodo ligula eget dolor. Aenean massa. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Donec quam felis, ultricies nec, pellentesque eu, pretium.."
  }
] 

Notice the issue from the API returning 400 error:

Cannot update epic with id xxx. hypothesis must be between 0 and 250 characters.

Expected Results

The hypothesis should apply the same restriction to both methods, UI and API

The limit aspect perhaps need to be defined by PdM

Actual Results

2 Different behaviour can be seen depending of the method used

Workaround

Currently there is no known workaround for this behavior, other than using the User interface for modifying this field. A workaround will be added here when available