How to build multimodule gradle project with each module having its own Open API spec and the parent has all spec merge together on build - gradle

Question

I am designing one application, the application should merge OpenAPI-3 specification files into a single file.
Consider the following open api v3 schema files color.yaml and book.yaml
color.yaml
openapi: 3.0.1
info:
title: OpenAPI definition
version: v0
servers:
- url: http://localhost:8080
description: Generated server url
paths:
/api/color/{name}:
get:
tags:
- color-controller
operationId: getColor
parameters:
- name: name
in: path
required: true
schema:
type: string
responses:
"200":
description: OK
content:
'*/*':
schema:
$ref: '#/components/schemas/Color'
components:
schemas:
Color:
type: object
properties:
name:
type: string
red:
type: integer
format: int32
green:
type: integer
format: int32
blue:
type: integer
format: int32
book.yaml
openapi: 3.0.1
info:
title: OpenAPI definition
version: v0
servers:
- url: http://localhost:8080
description: Generated server url
paths:
/api/book/{name}:
get:
tags:
- book-controller
operationId: getBook
parameters:
- name: name
in: path
required: true
schema:
type: string
responses:
"200":
description: OK
content:
'*/*':
schema:
$ref: '#/components/schemas/Book'
components:
schemas:
Book:
type: object
properties:
name:
type: string
iban:
type: string
</code>
The parent module should merge these files into a single master yaml spec file
**merged.yaml**
openapi: 3.0.1
info:
title: My title
version: 1.0.0-SNAPSHOT
servers:
- url: http://localhost:8080
description: Generated server url
paths:
/api/book/{name}:
get:
tags:
- book-controller
operationId: getBook
parameters:
- name: name
in: path
required: true
style: simple
explode: false
schema:
type: string
responses:
"200":
description: OK
content:
'*/*':
schema:
$ref: '#/components/schemas/Book'
/api/color/{name}:
get:
tags:
- color-controller
operationId: getColor
parameters:
- name: name
in: path
required: true
style: simple
explode: false
schema:
type: string
responses:
"200":
description: OK
content:
'*/*':
schema:
$ref: '#/components/schemas/Color'
components:
schemas:
Book:
type: object
properties:
name:
type: string
iban:
type: string
Color:
type: object
properties:
name:
type: string
red:
type: integer
format: int32
green:
type: integer
format: int32
blue:
type: integer
format: int32
Also when I do changes to specific sub-module spec file it should reflect in parent spec file and should show in swagger-ui for testing.

Answer 1

Regarding the merging part of your question:
You can use APIMatic's API spec merge feature to first merge your specs and then transform the merged output into OpenAPI's format. Here are the steps:
Structure your directory as follows:
dir\
spec1\
color.yaml
spec2\
book.yaml
APIMATIC-META.json
A minimalistic APIMATIC-META.json can look like this to enable merging:
{
"MergeConfiguration": {
"MergedApiName": "My title",
"MergeApis": true,
"MergeSettings": {
"SkipCodeGenValidation": true
}
}
}
ZIP the directory, upload it and transform it via their website to OpenAPI v3 to get your merged output. Here is a link that provides step by step guide on uploading and performing a transformation: https://docs.apimatic.io/manage-apis/api-merging/#transforming-the-zipped-file
If you are looking to automate the process, APIMatic has an API too: https://www.apimatic.io/docs/api#/http/api-endpoints/transformation/transform-via-file