[BUG][Java] ApiClient.java: error: no suitable method found for create(byte[],MediaType)

Created by: toby-murray-snow-software

Bug Report Checklist

Have you provided a full/minimal spec to reproduce the issue?
Have you validated the input using an OpenAPI validator (example)?
Have you tested with the latest master to confirm the issue still exists?
Have you searched for related issues/PRs?
[] What's the actual output vs expected output?
[Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

Using the java generator against a basic spec, the generated project fails to compile.

openapi-generator version

5.1.0 and latest master (docker image 3c6b0382cd49)

Regression from 5.0.1

OpenAPI declaration file content or url

openapi: 3.0.0
info:
  version: 1.0.0
  title: Api

paths:
  /version:
    get:
      tags:
      - version
      summary: Gets the system version check
      operationId: getVersion
      responses:
        200:
          description: Success
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/VersionGetResponse'

components:
  schemas:
    VersionGetResponse:
      type: string
      description: The version of this service
      required:
        - status
      properties:
        status:
          type: string
          description: OK

Generation Details

java -jar openapi-generator-cli-5.1.0.jar generate -g java -i service.yaml

Steps to reproduce

Run the generator as described above
Try to compile the code with ./gradlew compileJava or similar

Expected:

It will compile

Actual:

A bunch of:

out\java\src\main\java\org\openapitools\client\ApiClient.java:818: error: no suitable method found for create(byte[],MediaType)
            return RequestBody.create((byte[]) obj, MediaType.parse(contentType));
                              ^
    method RequestBody.create(MediaType,String) is not applicable
      (argument mismatch; byte[] cannot be converted to MediaType)
    method RequestBody.create(MediaType,ByteString) is not applicable
      (argument mismatch; byte[] cannot be converted to MediaType)
    method RequestBody.create(MediaType,byte[]) is not applicable
      (argument mismatch; byte[] cannot be converted to MediaType)
    method RequestBody.create(MediaType,File) is not applicable
      (argument mismatch; byte[] cannot be converted to MediaType)