[BUG][Ruby] Description `undefined method build_from_hash` in Ruby generated code

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?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

Error message: failed with the exception 'undefined method 'build_from_hash' for module Builder::Filter

Previous builds of my Ruby files for my gem using 7.14.0 generated code that contained:

      # Builds the object
      # @param [Mixed] Data to be matched against the list of oneOf items
      # @return [Object] Returns the model or the data itself
      def build(data)
        discriminator_value = data[openapi_discriminator_name]
        return nil if discriminator_value.nil?

        klass = openapi_discriminator_mapping[discriminator_value.to_s.to_sym]
        return nil unless klass

        resolved_klass = Builder.const_get(klass)
        resolved_klass.build(data)
    end

while version 7.17.0 generates

      # Builds the object
      # @param [Mixed] Data to be matched against the list of oneOf items
      # @return [Object] Returns the model or the data itself
      def build(data)
        discriminator_value = data[openapi_discriminator_name]
        return nil if discriminator_value.nil?

        klass = openapi_discriminator_mapping[discriminator_value.to_s.to_sym]
        return nil unless klass

        Builder.const_get(klass).build_from_hash(data)
      end

this last line, build_from_hash is blowing up my call, while the code generated with 7.14.0 successfully processes the same request.

openapi-generator version

7.17.0

OpenAPI declaration file content or url

files are the same between generated versions

Generation Details

$ openapi-generator generate -c generator-config.json

generator-config.json:

{
  "generatorName": "ruby",
  "inputSpec": "./builder.yaml",
  "outputDir": "./",
  "packageName": "my_builder",
  "gemName": "my_builder",
  "gemAuthor": "MyCompany",
  "gemHomepage": "https://github.com/<my_company>/builder-ruby-sdk",
  "gemVersion": "0.0.24",
  "moduleName": "Builder",
  "templateDir": "./templates"
}

Steps to reproduce

Related issues/PRs

Suggest a fix

Start with generator-config.json and the custom templates referenced by templateDir, then compare the Ruby output from 7.14.0 and 7.17.0 around the discriminator build method. Reproduce with builder.yaml and verify that the generated code handles the same request without the undefined build_from_hash error.