[API] [Admin/Partners] It is not possible to add a StreetCode while creating a partner./The partner is successfully created in the front, but Postman returns a 400 status code

[SophiaMRI]

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Environment: All Reproducible: Always Build found: 3341e9b

Preconditions

1. Open Postman.
2. Choose the POST method.
3. Enter valid endpoints.
4. At least 1 StreerCode has been created.

Steps to reproduce

1. Enter the valid&required data in the body, including the "streetcodes" array populated with an existing StreetCode id.
2. Click the 'Send' button.

Actual result

1. The '400 Bad Request' status with the 'An error occurred while saving the entity changes. See the inner exception for details.' message is returned in the response. But the partner is successfully created in the front.
2. The 'Стріткоди' field is empty in the created partner.

https://github.com/ita-social-projects/StreetCode/assets/135108144/01a5320b-92ae-48a6-aa12-1fce2f6ff3ab

Expected result

1. The '201 Created' status is returned in the response.
2. The 'Стріткоди' field in the created partner is populated with valid data.

User story and test case links User story #499 [Test case] #1315