[BUG][JAVA] Arrays in path parameters are encoded in the wrong way, leading to HTTP Bad Request

Description

The provided OpenAPI specification has array paramters as path parameters and the current generator generates wrong code for serialization by calling Array.toString() which leads to a string representation containing charaters ("[" and "]") that are not allowed within request path by spec.

openapi-generator version

openapi-generator-cli-4.3.1.jar

OpenAPI declaration file content or url

[...]
"/boards/boards/public/departure/{evaNumbers}": {
      "get": {
        "tags": [
          "Boards Public"
        ],
        "description": "Returns a departure board [Abfahrtstafel] for all public transports [Oeffentliche Verkehre].",
        "operationId": "boardDeparture",
        "parameters": [
          {
            "name": "evaNumbers",
            "in": "path",
            "description": "list of eva numbers of stations [Bahnhoefe] to get board for",
            "required": true,
            "schema": {
              "type": "array",
              "items": {
                "type": "string"
              }
            }
          },
[...]

Command line used for generation

java -jar openapi-generator-cli-4.3.1.jar generate -g java -i swagger.yml --library native --api-package innoapi.api --invoker-package innoapi.invoker --model-package innoapi.model

Steps to reproduce

Call this.boardsPublicAPI.boardDeparture(Arrays.asList("Test1", "Test2"), null, null, null, null, null, null, null, true);

Related issues/PRs

/

Suggest a fix

The problem is the generated code:
String localVarPath = "/boards/boards/public/departure/{evaNumbers}" .replace("{evaNumbers}", ApiClient.urlEncode(evaNumbers.toString()));

This leads to path parameters getting serialized as
[val1, val2]
but "[" and "]" are not allowed in path, hence a HTTP 400 = Bad Request is thrown.

Working solution and fix suggestion:
String localVarPath = "/boards/boards/public/departure/{evaNumbers}" .replace("{evaNumbers}", ApiClient.urlEncode(evaNumbers.stream().collect(Collectors.joining(","))));

Start by reproducing the Java client generated with openapi-generator-cli-4.3.1 using the supplied OpenAPI path parameter and the native library. Inspect the generated boardDeparture path serialization, then verify that array values no longer produce bracketed Array.toString() output and that the request succeeds without HTTP 400.