Fix Julia template for binary string

[qiaojunfeng]

It seems there is a small issue with generated julia function signature, when handling

application/octet-stream:
  schema:
    type: string
    format: binary

To better reproduce this, I set up a MWE here
https://github.com/qiaojunfeng/test-julia-OpenAPI/tree/main

Since this is a julia-specific issue, I will ping technical committee member @tanmaykm. Thanks!

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[wing328]

triggered CI tests via

• https://github.com/OpenAPITools/openapi-generator/actions/runs/12443478387/job/34742694987?pr=20364
• https://github.com/OpenAPITools/openapi-generator/actions/runs/12443477103/job/34742692216?pr=20364

and both tests passed

[tanmaykm]

Thanks @qiaojunfeng, I shall check this out this weekend.

[tanmaykm]

The effect of this change would be that if something is specified as binary format, it would now be generated as a String instread of Vector{UInt8} bytearray. While strings in Julia can contain invalid UTF8 bytecodes (https://docs.julialang.org/en/v1/manual/strings/), canonically Vector{UInt8} is used for such purposes.

I would like to understand more the reason why you feel we should have this changed in the openapi generated code?

[qiaojunfeng]

The effect of this change would be that if something is specified as binary format, it would now be generated as a String instread of Vector{UInt8} bytearray. While strings in Julia can contain invalid UTF8 bytecodes (https://docs.julialang.org/en/v1/manual/strings/), canonically Vector{UInt8} is used for such purposes.

I would like to understand more the reason why you feel we should have this changed in the openapi generated code?

Thanks @tanmaykm!
A concise answer to this is that with the current generator, the generated julia code does not work with binary string for file upload. Probably it is easier to understand this by running this example
https://github.com/qiaojunfeng/test-julia-OpenAPI/tree/main