[spring/spring-boot] API generation fails when specification refs a requestBody with object type schema

Created by: rhamiltonsf

Description

Using the following schema, the openapi-generator-maven-plugin fails to recognize the model in the requestBody schema, and instead tries to import and use a model named UNKNOWN_BASE_TYPE. This only happens when I use a ref to the requestBody and if the requestBody schema is of type object.

openapi-generator version

5.2.1 5.1.0 4.3.1

OpenAPI declaration file content or URL

Here is a minimum spec that reproduces the issue.

However note that this spec and this other spec both work.

Command line used for generation

This occurred using the openapi-generator-maven-plugin. See example pom here for configurations.

Steps to reproduce

create a new maven project using this pom.
Create src/main/resources directory and, add api.yaml to it
run mvn clean install from the pom directory

Expected Results: The command should execute successfully and generate default API models, interfaces, and delegate.

Actual Results:

[INFO] -------------------------------------------------------------
[ERROR] COMPILATION ERROR : 
[INFO] -------------------------------------------------------------
[ERROR] ~/testproject/target/generated-sources/openapi/api/org/openapitools/api/DefaultApi.java:[8,30] package org.openapitools.model does not exist
[ERROR] ~/testproject/target/generated-sources/openapi/api/org/openapitools/api/DefaultApiDelegate.java:[3,30] package org.openapitools.model does not exist
[ERROR] ~/testproject/target/generated-sources/openapi/api/org/openapitools/api/DefaultApi.java:[43,106] cannot find symbol
  symbol:   class UNKNOWN_BASE_TYPE
  location: interface org.openapitools.api.DefaultApi
[ERROR] ~/testproject/target/generated-sources/openapi/api/org/openapitools/api/DefaultApiDelegate.java:[33,43] cannot find symbol
  symbol:   class UNKNOWN_BASE_TYPE
  location: interface org.openapitools.api.DefaultApiDelegate