title: Open Api 3 generator does not generate classes for paths referenced by $ref
body: <p>I have following specification employee.yaml file:</p>
  <pre><code>openapi: 3.0.2
  info:
    title: Employee api
    version: 0.0.0
    description: Employee api specification
    contact:
      name: Lorem Ipsum
      email: lorem@ipsum.com
  
  tags:
    - name: &quot;Employee&quot;
    - name: &quot;EmployeeDisability&quot;
  
  paths:
    /employees:
      $ref: 'paths/employees.yaml'
  
  </code></pre>
  <p>and in /paths/employees.yaml</p>
  <pre><code>/employees:
      get:
        summary: This is summary
        tags:
          - 'Employee'
        description: This is description
        operationId: getEmployees
        responses:
          &quot;200&quot;:
            description: The request has succeeded - OK
            content:
              application/json:
                schema:
                  type: array
                  items:
                    $ref: '../dtos/employee.yaml'
  </code></pre>
  <p>When I copy code from <em>/paths/employees.yaml</em> and paste it into <em>employee.yaml</em> paths everything is generated correctly. I dont think this is a problem with path to file <em>employees.yaml</em>.
  Does anyone had similar problem?</p>
  <pre><code>&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot;?&gt;
  &lt;project xmlns=&quot;http://maven.apache.org/POM/4.0.0&quot;
           xmlns:xsi=&quot;http://www.w3.org/2001/XMLSchema-instance&quot;
           xsi:schemaLocation=&quot;http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd&quot;&gt;
      &lt;modelVersion&gt;4.0.0&lt;/modelVersion&gt;
  
      &lt;groupId&gt;org.example&lt;/groupId&gt;
      &lt;artifactId&gt;employees-service-spec&lt;/artifactId&gt;
      &lt;packaging&gt;jar&lt;/packaging&gt;
      &lt;version&gt;1.0-SNAPSHOT&lt;/version&gt;
  
      &lt;properties&gt;
          &lt;java.version&gt;11&lt;/java.version&gt;
          &lt;maven.compiler.source&gt;1.8&lt;/maven.compiler.source&gt;
          &lt;maven.compiler.target&gt;1.8&lt;/maven.compiler.target&gt;
          &lt;swagger-annotations-version&gt;1.5.22&lt;/swagger-annotations-version&gt;
          &lt;jersey-version&gt;2.27&lt;/jersey-version&gt;
          &lt;jackson-version&gt;2.10.2&lt;/jackson-version&gt;
          &lt;jodatime-version&gt;2.7&lt;/jodatime-version&gt;
          &lt;maven-plugin-version&gt;1.0.0&lt;/maven-plugin-version&gt;
          &lt;junit-version&gt;4.8.1&lt;/junit-version&gt;
          &lt;springfox-version&gt;2.9.2&lt;/springfox-version&gt;
          &lt;threetenbp-version&gt;1.3.8&lt;/threetenbp-version&gt;
          &lt;datatype-threetenbp-version&gt;2.6.4&lt;/datatype-threetenbp-version&gt;
          &lt;spring-boot-starter-test-version&gt;2.1.1.RELEASE&lt;/spring-boot-starter-test-version&gt;
          &lt;spring-boot-starter-web-version&gt;2.1.0.RELEASE&lt;/spring-boot-starter-web-version&gt;
          &lt;junit-version&gt;4.12&lt;/junit-version&gt;
          &lt;migbase64-version&gt;2.2&lt;/migbase64-version&gt;
          &lt;jackson-databind-nullable&gt;0.2.1&lt;/jackson-databind-nullable&gt;
      &lt;/properties&gt;
  
      &lt;dependencies&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;io.swagger&lt;/groupId&gt;
              &lt;artifactId&gt;swagger-annotations&lt;/artifactId&gt;
              &lt;version&gt;${swagger-annotations-version}&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.glassfish.jersey.core&lt;/groupId&gt;
              &lt;artifactId&gt;jersey-client&lt;/artifactId&gt;
              &lt;version&gt;${jersey-version}&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.glassfish.jersey.media&lt;/groupId&gt;
              &lt;artifactId&gt;jersey-media-multipart&lt;/artifactId&gt;
              &lt;version&gt;${jersey-version}&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.glassfish.jersey.media&lt;/groupId&gt;
              &lt;artifactId&gt;jersey-media-json-jackson&lt;/artifactId&gt;
              &lt;version&gt;${jersey-version}&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;com.fasterxml.jackson.jaxrs&lt;/groupId&gt;
              &lt;artifactId&gt;jackson-jaxrs-base&lt;/artifactId&gt;
              &lt;version&gt;${jackson-version}&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;com.fasterxml.jackson.core&lt;/groupId&gt;
              &lt;artifactId&gt;jackson-core&lt;/artifactId&gt;
              &lt;version&gt;${jackson-version}&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;com.fasterxml.jackson.core&lt;/groupId&gt;
              &lt;artifactId&gt;jackson-annotations&lt;/artifactId&gt;
              &lt;version&gt;${jackson-version}&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;com.fasterxml.jackson.core&lt;/groupId&gt;
              &lt;artifactId&gt;jackson-databind&lt;/artifactId&gt;
              &lt;version&gt;${jackson-version}&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;com.fasterxml.jackson.jaxrs&lt;/groupId&gt;
              &lt;artifactId&gt;jackson-jaxrs-json-provider&lt;/artifactId&gt;
              &lt;version&gt;${jackson-version}&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;com.fasterxml.jackson.datatype&lt;/groupId&gt;
              &lt;artifactId&gt;jackson-datatype-joda&lt;/artifactId&gt;
              &lt;version&gt;${jackson-version}&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;joda-time&lt;/groupId&gt;
              &lt;artifactId&gt;joda-time&lt;/artifactId&gt;
              &lt;version&gt;${jodatime-version}&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;com.brsanthu&lt;/groupId&gt;
              &lt;artifactId&gt;migbase64&lt;/artifactId&gt;
              &lt;version&gt;${migbase64-version}&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;junit&lt;/groupId&gt;
              &lt;artifactId&gt;junit&lt;/artifactId&gt;
              &lt;version&gt;${junit-version}&lt;/version&gt;
              &lt;scope&gt;test&lt;/scope&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.springframework.boot&lt;/groupId&gt;
              &lt;artifactId&gt;spring-boot-starter-test&lt;/artifactId&gt;
              &lt;version&gt;${spring-boot-starter-test-version}&lt;/version&gt;
              &lt;scope&gt;test&lt;/scope&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.springframework.boot&lt;/groupId&gt;
              &lt;artifactId&gt;spring-boot-starter-web&lt;/artifactId&gt;
              &lt;version&gt;${spring-boot-starter-web-version}&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;io.springfox&lt;/groupId&gt;
              &lt;artifactId&gt;springfox-swagger2&lt;/artifactId&gt;
              &lt;version&gt;${springfox-version}&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;io.springfox&lt;/groupId&gt;
              &lt;artifactId&gt;springfox-swagger-ui&lt;/artifactId&gt;
              &lt;version&gt;${springfox-version}&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.threeten&lt;/groupId&gt;
              &lt;artifactId&gt;threetenbp&lt;/artifactId&gt;
              &lt;version&gt;${threetenbp-version}&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;com.github.joschi.jackson&lt;/groupId&gt;
              &lt;artifactId&gt;jackson-datatype-threetenbp&lt;/artifactId&gt;
              &lt;version&gt;${datatype-threetenbp-version}&lt;/version&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.openapitools&lt;/groupId&gt;
              &lt;artifactId&gt;jackson-databind-nullable&lt;/artifactId&gt;
              &lt;version&gt;${jackson-databind-nullable}&lt;/version&gt;
          &lt;/dependency&gt;
  
  
          &lt;dependency&gt;
              &lt;groupId&gt;org.springframework.cloud&lt;/groupId&gt;
              &lt;artifactId&gt;spring-cloud-starter-openfeign&lt;/artifactId&gt;
              &lt;version&gt;3.0.2&lt;/version&gt;
          &lt;/dependency&gt;
      &lt;/dependencies&gt;
      &lt;build&gt;
          &lt;plugins&gt;
              &lt;plugin&gt;
                  &lt;groupId&gt;org.openapitools&lt;/groupId&gt;
                  &lt;artifactId&gt;openapi-generator-maven-plugin&lt;/artifactId&gt;
                  &lt;version&gt;5.1.0&lt;/version&gt;
                  &lt;executions&gt;
                      &lt;execution&gt;
                          &lt;id&gt;generate-java&lt;/id&gt;
                          &lt;goals&gt;
                              &lt;goal&gt;generate&lt;/goal&gt;
                          &lt;/goals&gt;
                          &lt;configuration&gt;
                              &lt;configOptions&gt;
                                  &lt;apiPackage&gt;com.example.demotest.api1&lt;/apiPackage&gt;
                                  &lt;dateLibrary&gt;java8&lt;/dateLibrary&gt;
                                  &lt;examples&gt;false&lt;/examples&gt;
                                  &lt;implicitHeaders&gt;false&lt;/implicitHeaders&gt;
                                  &lt;interfaceOnly&gt;false&lt;/interfaceOnly&gt;
                                  &lt;library&gt;spring-cloud&lt;/library&gt;
                                  &lt;modelPackage&gt;com.example.demotest.model1&lt;/modelPackage&gt;
                                  &lt;returnSuccessCode&gt;true&lt;/returnSuccessCode&gt;
                                  &lt;swaggerDocketConfig&gt;true&lt;/swaggerDocketConfig&gt;
                                  &lt;unhandledException&gt;true&lt;/unhandledException&gt;
                                  &lt;useOptional&gt;false&lt;/useOptional&gt;
                                  &lt;useTags&gt;true&lt;/useTags&gt;
                              &lt;/configOptions&gt;
                              &lt;generatorName&gt;spring&lt;/generatorName&gt;
                              &lt;typeMappings&gt;
                                  &lt;typeMapping&gt;OffsetDateTime=Instant&lt;/typeMapping&gt;
                              &lt;/typeMappings&gt;
                              &lt;importMappings&gt;Problem=org.zalando.problem.Problem,java.time.OffsetDateTime=java.time.Instant&lt;/importMappings&gt;
                              &lt;inputSpec&gt;${project.basedir}/src/main/resources/employees-service-spec/employee/employee.yaml&lt;/inputSpec&gt;
                              &lt;modelNameSuffix&gt;DTO&lt;/modelNameSuffix&gt;
                              &lt;skipValidateSpec&gt;true&lt;/skipValidateSpec&gt;
                          &lt;/configuration&gt;
                      &lt;/execution&gt;
                  &lt;/executions&gt;
              &lt;/plugin&gt;
  
          &lt;/plugins&gt;
      &lt;/build&gt;
  &lt;/project&gt;
  </code></pre>
  <p><a href="https://i.stack.imgur.com/oguqS.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/oguqS.png" alt="project structure" /></a></p>
  <p>Maybe there are other limitations that I haven't found?</p>