JsonIgnore using Open API spec

I use OpenAPI spec to generate Java POJOs. What do I need to specify in Open API yaml to generate the equivalent of below POJO ?

...
@JsonIgnore
public String ignoredProperty;
...

I have the yaml spec as below

openapi: 3.0.0
info:
  title: Cool API
  description: A Cool API spec
  version: 0.0.1
servers:
  - url: http://api.cool.com/v1
    description: Cool server for testing
paths:
  /
  ...
components:
  schemas:
    MyPojo:
      type: object
      properties:
        id:
          type: integer
        name:
          type: string
        # I want the below attribute to be ignored as a part of JSON 
        ignoreProperty:  
          type: string

Solution

the openapi generator supports vendor extensions. Specifically, for the Java generator, it supports the following extensions as of the time of writing. However, an up-to-date list can be found here.

Extension name	Description	Applicable for	Default value
x-discriminator-value	Used with model inheritance to specify value for discriminator that identifies current model	MODEL
x-implements	Ability to specify interfaces that model must implements	MODEL	empty array
x-setter-extra-annotation	Custom annotation that can be specified over java setter for specific field	FIELD	When field is array & uniqueItems, then this extension is used to add `@JsonDeserialize(as = LinkedHashSet.class)` over setter, otherwise no value
x-tags	Specify multiple swagger tags for operation	OPERATION	null
x-accepts	Specify custom value for 'Accept' header for operation	OPERATION	null
x-content-type	Specify custom value for 'Content-Type' header for operation	OPERATION	null
x-class-extra-annotation	List of custom annotations to be added to model	MODEL	null
x-field-extra-annotation	List of custom annotations to be added to property	FIELD	null
x-webclient-blocking	Specifies if method for specific operation should be blocking or non-blocking(ex: return `Mono<T>/Flux<T>` or `return T/List<T>/Set<T>` & execute `.block()` inside generated method)	OPERATION	false

You can use the x-field-extra-annotation vendor extension listed above to add annotations to any field. So, for your example, you can add the following:

openapi: 3.0.0
info:
  title: Cool API
  description: A Cool API spec
  version: 0.0.1
servers:
  - url: http://api.cool.com/v1
    description: Cool server for testing
paths:
  /
  ...
components:
  schemas:
    MyPojo:
      type: object
      properties:
        id:
          type: integer
        name:
          type: string
        # I want the below attribute to be ignored as a part of JSON 
        ignoreProperty:  
          type: string  
          x-field-extra-annotation: "@com.fasterxml.jackson.annotation.JsonIgnore"