An OpenAPI definition for GeoJSON with Geometry and Features.

geometry_geojson.yaml

# MIT License
#
# Copyright (c) 2017 Daniele Andreis <daniele.andreis@gmail.com>
#
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# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
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# The above copyright notice and this permission notice shall be included in all
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

swagger: '2.0'
info:
  version: "1.0.0"
  title: GeoJSON geometry
  description: An example of an OpenAPI definition for GeoJSON with Geometry and Features.
  termsOfService: "no"
  contact:
    name:  Tim Telcik
    email: tim.telcik@minetec.com.au
    url: ""
  license:
    name: GPLv3
    url: https://www.gnu.org/licenses/gpl-3.0.html
externalDocs:
  description: RFC7946 - The GeoJSON format.
  url: https://tools.ietf.org/html/rfc7946
schemes:
  - http
host: myHost
basePath: /v1
consumes:
  - "application/json"
produces:
  - "application/json"

securityDefinitions:
  UserSecurity:
    type: basic
  # AdminSecurity:
  #   type: basic
  # MediaSecurity:
  #   type: basic
#globalmente e' userSecurity ma posso cambiare localmente

security:
  - UserSecurity: []

paths:
  /geometries:
    get:
      summary: GeoJSON geometry array
      responses:
        200:
          description: Successful response
          schema:
            type: array
            items:
              $ref: "#/definitions/GeometryCollection"

        400:
          $ref: "#/responses/BadRequest400ErrorResponse"
        401:
          $ref: "#/responses/Unauthorized401ErrorResponse"
        500:
          $ref: "#/responses/Standard500ErrorResponse"

    post:
      summary: Create new geometry
      parameters:
        - name: geom
          in: body
          required: true
          schema:
            $ref: "#/definitions/Geometry"
      responses:
        201:
          description: new geometry created
        400:
          $ref: "#/responses/BadRequest400ErrorResponse"
        401:
          $ref: "#/responses/Unauthorized401ErrorResponse"
        403:
          $ref: "#/responses/Forbidden403ErrorResponse"
        500:
          $ref: "#/responses/Standard500ErrorResponse"

definitions:
  Error:
    required:
      - code
      - message
    properties:
      code:
        type: string
      message:
        type: string

  Geometry:
    type: object
    description: GeoJSon geometry
    discriminator: type
    required:
      - type
    externalDocs:
      url: http://geojson.org/geojson-spec.html#geometry-objects
    properties:
      type:
        type: string
        enum:
        - Point
        - LineString
        - Polygon
        - MultiPoint
        - MultiLineString
        - MultiPolygon
        description: the geometry type

  Point3D:
    type: array
    description: Point in 3D space
    externalDocs:
      url: http://geojson.org/geojson-spec.html#id2
    minItems: 2
    maxItems: 3
    items:
      type: number

  Point:
    type: object
    description: GeoJSon geometry
    externalDocs:
      url: http://geojson.org/geojson-spec.html#id2
    allOf:
      - $ref: "#/definitions/Geometry"
      - properties:
          coordinates:
            $ref: '#/definitions/Point3D'

  LineString:
    type: object
    description: GeoJSon geometry
    externalDocs:
      url: http://geojson.org/geojson-spec.html#id3
    allOf:
      - $ref: "#/definitions/Geometry"
      - properties:
          coordinates:
            type: array
            items:
              $ref: '#/definitions/Point3D'

  Polygon:
    type: object
    description: GeoJSon geometry
    externalDocs:
      url: http://geojson.org/geojson-spec.html#id4
    allOf:
      - $ref: "#/definitions/Geometry"
      - properties:
          coordinates:
            type: array
            items:
              type: array
              items:
                $ref: '#/definitions/Point3D'

  MultiPoint:
    type: object
    description: GeoJSon geometry
    externalDocs:
      url: http://geojson.org/geojson-spec.html#id5
    allOf:
      - $ref: "#/definitions/Geometry"
      - properties:
          coordinates:
            type: array
            items:
              $ref: '#/definitions/Point3D'

  MultiLineString:
    type: object
    description: GeoJSon geometry
    externalDocs:
      url: http://geojson.org/geojson-spec.html#id6
    allOf:
      - $ref: "#/definitions/Geometry"
      - properties:
          coordinates:
            type: array
            items:
              type: array
              items:
                $ref: '#/definitions/Point3D'


  MultiPolygon:
    type: object
    description: GeoJSon geometry
    externalDocs:
      url: http://geojson.org/geojson-spec.html#id6
    allOf:
      - $ref: "#/definitions/Geometry"
      - properties:
          coordinates:
            type: array
            items:
              type: array
              items:
                type: array
                items:
                  $ref: '#/definitions/Point3D'

  GeometryCollection:
    type: object
    description: GeoJSon geometry collection
    required:
     - type
     - geometries
    externalDocs:
      url: http://geojson.org/geojson-spec.html#geometrycollection
    properties:
      type:
        type: string
        enum:
        - GeometryCollection
      geometries:
        type: array
        items:
          $ref: '#/definitions/Geometry'

  Feature:
    type: object
    description: GeoJSon Feature
    required:
     - type
     - id
     - geometry
    externalDocs:
      url: https://tools.ietf.org/html/rfc7946#section-3.2
    properties:
      type:
        type: string
        enum:
          - Feature
      id:
        type: integer
      geometry:
        $ref: '#/definitions/GeometryCollection'
      properties:
        type: object

  FeatureCollection:
    type: object
    description: GeoJSon Feature collection
    required:
     - type
     - features
    externalDocs:
      url: https://tools.ietf.org/html/rfc7946#section-3.3
    properties:
      type:
        type: string
        enum:
        - FeatureCollection
      features:
        type: array
        items:
          $ref: '#/definitions/Feature'

responses:
  Standard500ErrorResponse:
    description: An unexpected error occured.
    schema:
      $ref: "#/definitions/Error"

  BadRequest400ErrorResponse:
    description: The JSON is not valid
    schema:
      $ref: "#/definitions/Error"

  Unauthorized401ErrorResponse:
    description: The request requires an user authentication
    schema:
      $ref: "#/definitions/Error"

  Forbidden403ErrorResponse:
    description: the access is not allowed
    schema:
      $ref: "#/definitions/Error"

  # NotFound404ErrorResponse:
  #   description: not found check the path or the query
  #   schema:
  #     $ref: "#/definitions/Error"

  # Ok200Response:
  #   description: Eyerything is working
  #   schema:
  #     $ref: "#/definitions/OK"

  # Create201Response:
  #   description:  New resource has been created
  #   schema:
  #     $ref: "#/definitions/OK"

  # Delete204Response:
  #   description: The resource was successfully deleted
  #   schema:
  #     $ref: "#/definitions/OK"

good

Thank you for sharing, this was really helpful for me!
A couple of suggestions:

• Geometry > properties > type > enum is missing the option GeometryCollection (listed in https://datatracker.ietf.org/doc/html/rfc7946#section-1.4)
• The id property of Feature is optional (see https://datatracker.ietf.org/doc/html/rfc7946#section-3.2) so it should not be in Feature > required
• The id property of Feature can be a string or a number (see https://datatracker.ietf.org/doc/html/rfc7946#section-3.2) so Feature > properties > id should be anyOf type: string or type: integer
• Any GeoJSON object may optionally have a bbox property (see https://datatracker.ietf.org/doc/html/rfc7946#section-5) with a schema similar to:

    BoundingBox:
      type: array
      externalDocs:
        url: https://tools.ietf.org/html/rfc7946#section-5
      minItems: 4
      maxItems: 6
      items:
        type: number