[cpprest] JSON format:byte incorrectly converted to ByteArray

Description

JSON element with {"type": "string", "format": "byte"} is being translated to unknown type 'ByteArray'. The ByteArray.h file being included as a result fails compilation. It appears like similar problems were fixed for Java, C#, and potentially other libraries.

Swagger-codegen version

2.3.1

Swagger declaration file content or url

"key": {
          "description": "key is the key in bytes. An empty key is not allowed.",
          "type": "string",
          "format": "byte"
        },

Command line used for generation

java -jar swagger-codegen-cli.jar generate -l cpprest -i example.yaml -o example/src/

Steps to reproduce

The swagger JSON snippet above results in the following generated C++ snippet:

...
#include "ByteArray.h"
...

/// key is the key in bytes. An empty key is not allowed.
ByteArray getKey() const;
bool keyIsSet() const;
void unsetKey();
void setKey(ByteArray value);

This should probably be just string

Related issues/PRs

Similar issue for Java: https://github.com/swagger-api/swagger-codegen/issues/4824
Similar issue for C#: https://github.com/swagger-api/swagger-codegen/issues/3554

Suggest a fix/enhancement

Reproduce the issue with the shown swagger-codegen-cli command and the cpprest generator, then trace how a string with format byte becomes the generated ByteArray.h include and accessors. Done means the generated C++ uses string instead of the unknown ByteArray type and compiles successfully.