Generated Java APIs incorrectly encode commas in certain query parameters

Description

For a query parameter of type "array" and collectionFormat "csv", the Java generated API percent-encodes the commas that separate the individual values. This is incorrect behaviour, as the commas are used as delimiters, not data, and should not be encoded.

For example, the following:

/test?param=a,b,c

becomes:

/test?param=a%2Cb%2Cc

Swagger-codegen version

2.2.0

Swagger declaration file content or url

The following Swagger spec demonstrates this behaviour:

{
  "swagger": "2.0",
  "info": {
    "title": "test spec",
    "version": "1.0"
  },
  "parameters": {
    "testParam": {
      "name": "test",
      "in": "query",
      "type": "array",
      "items": {
        "type": "string"
      },
      "collectionFormat": "csv"
    }
  },
  "paths": {
    "/test": {
      "get": {
        "description": "test get",
        "parameters": [
          {
            "$ref": "#/parameters/testParam"
          }
        ],
        "references": {

        }
      }
    }
  }
}

Command line used for generation

C:\Users\mkourlas\Downloads\swagger-codegen-2.2.0>java -jar modules\swagger-code
gen-cli\target\swagger-codegen-cli.jar generate -Dlibrary=jersey1 -i swagger.jso
n -l java -o test\java

Steps to reproduce

1. Generate and build the Java API for the above specification.
2. Create a new DefaultApi instance.
3. Call the testGet function with several strings a List passed to the test parameter.
4. The API will send an HTTP request with a URI looking like the following:

/test?test=string1%2Cstring2%2Cstring3

This should instead be

/test?test=string1,string2,string3

Suggest a Fix

This is caused by the following parts of the generated code:

  public void testGet(List<String> test) throws ApiException {
    [...]
    // query params
    List<Pair> localVarQueryParams = new ArrayList<Pair>();
    [...]
    localVarQueryParams.addAll(apiClient.parameterToPairs("csv", "test", test));
    [...]
    apiClient.invokeAPI(localVarPath, "GET", localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarFormParams, localVarAccept, localVarContentType, localVarAuthNames, null);
  }

  private String buildUrl(String path, List<Pair> queryParams) {
    final StringBuilder url = new StringBuilder();
    url.append(basePath).append(path);

    if (queryParams != null && !queryParams.isEmpty()) {
      // support (constant) query string in `path`, e.g. "/posts?draft=1"
      String prefix = path.contains("?") ? "&" : "?";
      for (Pair param : queryParams) {
        if (param.getValue() != null) {
          if (prefix != null) {
            url.append(prefix);
            prefix = null;
          } else {
            url.append("&");
          }
          String value = parameterToString(param.getValue());
          url.append(escapeString(param.getName())).append("=").append(escapeString(value));
        }
      }
    }
  }

The generated API can't just escape the entire parameter value in buildUrl. It should be escaping the individual comma-separated values as part of the parameterToPairs function while leaving the commas alone, and then simply appending the parameter value to the URL without escaping in buildUrl.

Start with the generated Java client flow shown in the issue: parameterToPairs and ApiClient buildUrl, then reproduce the request using the supplied Swagger declaration and generation command. Done means csv query parameters preserve commas as delimiters while individual values remain correctly escaped.