[BUG] [JAVA] Client generator generates ByteArrayInputStream instead of String for url encoded forms

Bug Report Checklist

Description

When generating a client from a json schema, the requestBody of our login form is translated to use a byteArrayInputStream with the form information as an outputStream. This makes the requestBody show up as empty when trying to use SSL through a proxy to send a request.
There should be no reason to need an inputStream instead of just a normal string as content, seeing as the rest of the http requests are all turned into a string as well.

openapi-generator version

openapi-generator-maven-plugin 7.11.0

OpenAPI declaration file content or url

"/auth/login" : {
      "post" : {
        "tags" : [ "Auth" ],
        "operationId" : "login",
        "parameters" : [ {
          "name" : "loginThing",
          "in" : "header",
          "schema" : {
            "type" : "boolean",
            "default" : true
          }
        } ],
        "requestBody" : {
          "content" : {
            "application/x-www-form-urlencoded" : {
              "schema" : {
                "type" : "object",
                "properties" : {
                  "username" : {
                    "type" : "string"
                  },
                  "password" : {
                    "type" : "string"
                  }
                }
              }
            }
          }
        },
        "responses" : {
        "default" : {
            "description" : "default response",
            "content" : {
              "application/json" : { }
            }
          }
        }
      }
    }

Steps to reproduce

using openapi-generator-maven-plugin in your pom.xml

• set the input spec to point to a json containing something like the call above
• I have supportUrlQuery=false because of requirements elsewhere in the json, don't know if this matters.
• run mvn clean package
• check the generated code of the client for

localVarRequestBuilder.header("Content-Type", entity.getContentType().getValue()).method("POST", BodyPublishers.ofInputStream(() -> new ByteArrayInputStream(formOutputStream.toByteArray())));

Start with the OpenAPI Generator Java client output produced by the openapi-generator-maven-plugin 7.11.0, using the supplied JSON schema and running mvn clean package. Inspect the generated request for application/x-www-form-urlencoded, especially the BodyPublishers.ofInputStream call and formOutputStream handling. Done means the generated request sends the encoded form content correctly through the reported proxy scenario without using an input stream.