Name collisions with new RingCentral OpenAPI 2.0 spec and OpenAPI Generator 4.0.0

[grokify]

Attempting to build the SDK using the new RingCentral OpenAPI 2.0 spec and OpenAPI Generator 4.0.0 SNAPSHOT (openapi-generator-cli-4.0.0-20190302.141844-340.jar) results in the following collisions.

$ go run get_me.go 
../../ringcentral/api_sms_and_mms.go:42:6: DeleteMessageOpts redeclared in this block
	previous declaration at ../../ringcentral/api_internal_messages.go:135:6
../../ringcentral/api_sms_and_mms.go:128:6: DeleteMessagesByFilterOpts redeclared in this block
	previous declaration at ../../ringcentral/api_internal_messages.go:221:6
../../ringcentral/api_sms_and_mms.go:218:6: GetMessageAttachmentByIdOpts redeclared in this block
	previous declaration at ../../ringcentral/api_internal_messages.go:311:6
../../ringcentral/api_sms_and_mms.go:314:6: ListMessagesOpts redeclared in this block
	previous declaration at ../../ringcentral/api_internal_messages.go:407:6
../../ringcentral/api_sms_and_mms.go:657:6: SyncMessagesOpts redeclared in this block
	previous declaration at ../../ringcentral/api_internal_messages.go:657:6
../../ringcentral/api_sms_and_mms.go:657:6: too many errors

This occurs because the API endpoint is tagged with multiple tags and OpenAPI Generator creates a non-namespaced options struct for each namespaced endpoint.

  /restapi/v1.0/account/{accountId}/extension/{extensionId}/message-store/{messageId}:
    get:
      tags:
      - Fax
      - SMS and MMS
      - Internal Messages

[grokify]

Possible solutions:

1. only create models once if multiple tags exist. This will allow existing naming conventions to stay the same. This seems reasonable given that the multiple tags indicate the auto-generated parameter structs can be exactly the same. This is backward compatible.
2. add a namespace to the opts. This is not backward compatible.

[grokify]

Some investigation into tags. If we can identify and map API service to the tag, then we can only write the Opts struct with the first tag.

Adding the following to api.mustache

{{#tags}}
{{tags}}
{{/tags}}

Results in the following being written out in the API go file:

[class Tag {
    name: Fax
    description: null
    externalDocs: null
}, class Tag {
    name: SMS and MMS
    description: null
    externalDocs: null
}, class Tag {
    name: Internal Messages
    description: null
    externalDocs: null
}]
[class Tag {
    name: Fax
    description: null
    externalDocs: null
}, class Tag {
    name: SMS and MMS
    description: null
    externalDocs: null
}, class Tag {
    name: Internal Messages
    description: null
    externalDocs: null
}]
[class Tag {
    name: Fax
    description: null
    externalDocs: null
}, class Tag {
    name: SMS and MMS
    description: null
    externalDocs: null
}, class Tag {
    name: Internal Messages
    description: null
    externalDocs: null
}]

[grokify]

Closing due to new tagging approach.