No converter for org.springframework.ai.openai.api.ResponseFormat

I have a Spring Boot (version 3.4.2) application with Spring AI and I want to get only JSON responses from OpenAI, so I configured it in my application.yml file, see Built-in JSON mode:

Some AI Models provide dedicated configuration options to generate structured (usually JSON) output.

OpenAI Structured Outputs can ensure your model generates responses conforming strictly to your provided JSON Schema. You can choose between the JSON_OBJECT that guarantees the message the model generates is valid JSON or JSON_SCHEMA with a supplied schema that guarantees the model will generate a response that matches your supplied schema (spring.ai.openai.chat.options.responseFormat option).

Unfortunately, it is not working.

Configuration

spring:
  ai:
    openai:
      chat:
        options:
          model: gpt-4o-mini
          temperature: 0.0
          responseFormat: JSON_SCHEMA

Logs

Failed to bind properties under 'spring.ai.openai.chat.options.response-format' to org.springframework.ai.openai.api.ResponseFormat:

    Reason: org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type [java.lang.String] to type [@com.fasterxml.jackson.annotation.JsonProperty org.springframework.ai.openai.api.ResponseFormat]

Research

I looked into ResponseFormat and ResponseFormat.Type and changed JSON_SCHEMA to json_schema but it didn't help.
I read Using the Chat Options Builder and tried to add the response format programmatically. But then I can no longer use BeanOutputConverter and have to write the JSON schema manually instead of getting it dynamically from the Java class.

Question

What did I wrong? How can I configure the response format in my application.yml?

Solution

The name of the property is spring.ai.openai.chat.options.response-format.type, see Configuring via Application Properties:

Configuring via Application Properties

Alternatively, when using the OpenAI auto-configuration, you can configure the desired response format through the following chat application properties:

spring.ai.openai.api-key=YOUR_API_KEY
spring.ai.openai.chat.options.model=gpt-4o-mini
spring.ai.openai.chat.options.response-format.type=JSON_SCHEMA
spring.ai.openai.chat.options.response-format.name=MySchemaName
spring.ai.openai.chat.options.response-format.schema={"type":"object","properties":{"steps":{"type":"array","items":{"type":"object","properties":{"explanation":{"type":"string"},"output":{"type":"string"}},"required":["explanation","output"],"additionalProperties":false}},"final_answer":{"type":"string"}},"required":["steps","final_answer"],"additionalProperties":false}
spring.ai.openai.chat.options.response-format.strict=true

The modified application.yml:

spring:
  ai:
    openai:
      chat:
        options:
          model: gpt-4o-mini
          temperature: 0.0
          response-format: 
            type: json-schema