Steps to reproduce:

1. Install Legacy Bridge.
2. Create a new class with any name and add a single ezdate fieldtype with no required and empty default value.
3. Create new Content of the class created in step 2.
4. Save it without changing the date.

Result:

When creating a new Content its date you can see is set to 31.12.1969.

After saving the Content its date is saved as 31.12.1969.

Expected result:

When creating a new Content the date should be empty.

After saving Content the date should be empty as well.