[BUG] [JAVA] Generated class with no fields instead of a primitive String

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator?
• 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?
  Actual output:

  public class Result  {
   @ApiModelProperty(required = true, value = "This is the result string ")
   /**
     * This is the result string 
    **/
    private String resultId;

    @ApiModelProperty(value = "")
    @Valid
    private ResultBban bban;

    // ... accessors etc.
  }

  public class ResultBban  {
    // no fields, only the default methods
    public boolean equals(Object o)...
    public int hashCode()...
    public String toString()...
    private static String toIndentedString(Object o)...
  }

Expected output:

  public class Result  {
   @ApiModelProperty(required = true, value = "This is the result string ")
   /**
     * This is the result string 
    **/
    private String resultId;

  @ApiModelProperty(example = "BARC12345612345678", value = "Basic Bank Account Number (BBAN) Identifier. ")
   /**
     * Basic Bank Account Number (BBAN) Identifier. 
    **/
    private String bban;


    // ... accessors, pattern annotation, etc.
  }

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Description

When using anyOf property with description and ref (which is of type string), the plugin up to 7.10.0 properly generated a model class with a String field. Since 7.11.0 (including current 7.14.0 and master) it instead generates a field whose type is a separate generated model class that itself has no fields.

openapi-generator version

7.11.0-7.14.0
(it's a regression - 7.10.0 was ok)

OpenAPI declaration file content or url

openapi: 3.0.1
info:
  version: 1.0.0
  title: Test
paths:
  /api/test:
    get:
      operationId: getTest
      responses:
        '200':
          description: Successful operation
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Result'
components:
  schemas:
    Result:
      description: |
        The test result
      type: object
      required:
        - resultId
      properties:
        resultId:
          description: |
              This is the result string
          type: string
        bban:
          anyOf:
            - description: |
                This is the BBAN string
            - $ref: '#/components/schemas/BBAN'
    BBAN:
      description: |
        Basic Bank Account Number (BBAN) Identifier.
      type: string
      pattern: "[a-zA-Z0-9]{1,30}"
      example: "BARC12345612345678"

Generation Details

       <plugin>
         <groupId>org.openapitools</groupId>
         <artifactId>openapi-generator-maven-plugin</artifactId>
         <version>7.10.0</version>
         <configuration>
             <generateModelTests>false</generateModelTests>
             <generateApiTests>false</generateApiTests>
             <generateModelDocumentation>false</generateModelDocumentation>
             <generateApiDocumentation>false</generateApiDocumentation>
             <skipIfSpecIsUnchanged>true</skipIfSpecIsUnchanged>
             <addTestCompileSourceRoot>false</addTestCompileSourceRoot>
             <addCompileSourceRoot>true</addCompileSourceRoot>
             <configHelp>false</configHelp>
             <configOptions>
                 <java8>true</java8>
                 <interfaceOnly>true</interfaceOnly>
                 <dateLibrary>java8</dateLibrary>
                 <openApiNullable>false</openApiNullable>
                 <containerDefaultToNull>true</containerDefaultToNull>
                 <serializationLibrary>jackson</serializationLibrary>
                 <sourceFolder>src/main/java</sourceFolder>
                 <legacyDiscriminatorBehavior>false</legacyDiscriminatorBehavior>
                 <inputSpec>${project.basedir}/src/main/resources/test.yaml</inputSpec>
             </configOptions>
         </configuration>
         <executions>
           <execution>
             <id>generate-test</id>
               <goals>
                   <goal>generate</goal>
               </goals>
               <configuration>
                 <generatorName>jaxrs-cxf</generatorName>
                 <inputSpec>${project.basedir}/src/main/resources/test.yaml</inputSpec>
                 <output>${project.build.directory}/generated</output>
               </configuration>
           </execution>
         </executions>
      </plugin>

Steps to reproduce

run a maven build with the above plugin configuration in the pom and the above yaml in the resources dir.

Related issues/PRs

The symptoms seem the same as #20630, but that one metnions allOf while here we have anyOf, and in addition that issue is marked as closed before 7.14.0 while I'm still experiencing it on current 7.14.0/master.

Start by running the Maven configuration with the supplied resources/test.yaml and jaxrs-cxf generator, comparing generation on 7.10.0 with 7.11.0 or later. Trace how the anyOf property combines its description with the BBAN string reference; done means bban is generated as a String with its pattern and example, without an empty BBAN model class.