Actions require an explicit HttpMethod binding for Swagger/OpenAPI 3.0

Yes, that's correct. In Swagger/OpenAPI 3.0, it's mandatory to specify the HTTP method for each API endpoint. This is typically done using the `get`, `post`, `put`, `delete` and other similar keywords in the API definition. If the method is not specified, the Swagger/OpenAPI specification will not be valid, and the API will not be able to be properly documented or used by clients.

To specify the HTTP method for an endpoint in Swagger/OpenAPI 3.0, you can use the following syntax:

paths:
  /users:
    get:
      summary: Get a list of users
      description: Retrieve a list of user objects
      responses:
        '200':
          description: A list of user objects
    post:
      summary: Add a new user
      description: Add a new user object
      responses:
        '201':
          description: The newly created user object

In the above example, there are two endpoints under the `/users` path: `GET` and `POST`. Each endpoint specifies the HTTP method explicitly using the `get` and `post` keywords. Additionally, you can provide a summary, a description and response examples for each endpoint, to help document and understand their behavior.