Response for Controller with type of "Map of Map" is not properly generated.

[iliapastushenko]

Describe the bug

I have next controller method

public Map<String, Map<String, String>> getContent()

I need to describe this response in the yml.

Tried this option:

  responses:
    '200':
      description: successful operation
      content:
        '*/*':
          schema:
            type: object
            additionalProperties:
              type: object
              additionalProperties:
                type: string

But this generates next interface:

default ResponseEntity<Map<String, Map<String>> getContent
so obviously this code has compilation error.

I tried other options for yml - nothing works.
Looks like a bug.

To Reproduce:
Mentioned above.

Expected behavior:
Properly generated code: default ResponseEntity<Map<String, Map<String,String>>> getContent ()

Environment

Plugin version: 2.19.2
Gradle version: 7.1
Java version: openjdk version "16" 2021-03-16 OpenJDK Runtime Environment (build 16+36-2231)
OS: masOS Big Sur Version 11.5.2

Dependencies are:

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-web:2.7.0'
    implementation 'io.swagger.core.v3:swagger-annotations:2.2.0'
    implementation 'io.springfox:springfox-swagger2:3.0.0'
    implementation group: 'javax.validation', name: 'validation-api', version: '2.0.1.Final'
    swaggerCodegen 'org.openapitools:openapi-generator-cli:6.0.0'
}