How to parse unicode characters correctly in rest interfaces for fields of type string(byte)?

Summary:

When I create a requistion via rest api,there used one param of string(byte) type,and incoming content contains special character like that"\u25cf". however,it's failed to convert to ●

• Bollow is a screenshot of the result of the conversion using the online tool

• Who has successful experience in this issue? pls share me

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