[BUG] JSON serialized query-parameters are generated wrong

[davidkarlsen]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• What's the version of OpenAPI Generator used?
• Have you search for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Bounty to sponsor the fix (example)

Description

https://swagger.io/docs/specification/describing-parameters/#schema-vs-content states that query params with content application/json will be:
filter={"type":"t-shirt","color":"blue"}, but it generated like:

    public AccountListResponseType accountList(@QueryParam("customerId") @NotNull String customerId, @QueryParam("pagingInputElement")  UNKNOWN_PARAMETER_NAME);
```

##### openapi-generator version
3.3.4

##### OpenAPI declaration file content or url

```
 get:
      tags:
        - Account resource
      summary: list accounts
      operationId: accountList
      parameters:
        - name: customerId
          required: true
          in: query
          schema:
            type: string
        - name: pagingInputElement
          # required: true
          in: query
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/PagingInputElementType'
```

##### Command line used for generation

```
 <configuration>
              <inputSpec>${project.basedir}/src/main/resources/META-INF/resources/api-v1.yaml</inputSpec>
              <validateSpec>true</validateSpec>
              <generatorName>jaxrs-cxf</generatorName>
              <generateSupportingFiles>false</generateSupportingFiles>
              <generateApiTests>false</generateApiTests>
              <generateModelDocumentation>false</generateModelDocumentation>
              <withXml>true</withXml>
              <!-- https://github.com/OpenAPITools/openapi-generator/blob/master/docs/generators/jaxrs-cxf.md -->
              <configOptions>
                <!-- important to add this or else codegen is malfunctioning: -->
                <sourceFolder>src/gen/java/main</sourceFolder>
                <interfaceOnly>true</interfaceOnly>
                <useJackson>true</useJackson>
                <dateLibrary>java8</dateLibrary>
                <serializableModel>true</serializableModel>
                <java8>true</java8>
                <booleanGetterPrefix>is</booleanGetterPrefix>
                <useBeanValidation>true</useBeanValidation>
                <addConsumesProducesJson>true</addConsumesProducesJson>
              </configOptions>
```

##### Steps to reproduce

See above

##### Related issues/PRs

N/A

##### Suggest a fix

generate properly named parameter of proper type

[davidkarlsen]

Related to spec discussion OAI/OpenAPI-Specification#1706

[kaburke]

The referenced discussion doesn't seem to address the issue. This bug report is concerning parameters using the content property, allowing for the specification of the content type. This bug is pointing out that when the content is set to application/json, the generator ignores the specification. The generated client doesn't pass json data, as requested.

[hejianchao]

Is there any progress on this issue?