Generating Multiple Path Bindings for Single gRPC Call

I have a field in a protobuf message called "parent". It looks like this:

message ListRolesRequest {
    // The resource name of the parent resource in one of the following formats:
    // `` (empty string) -- this refers to curated roles.
    // `organizations/{organization_id}`
    // `tenants/{tenant_id}`
    string parent = 1;
  ...
}

And a gRPC method that looks like this:

rpc ListRoles(ListRolesRequest) returns (ListRolesResponse) {
      option (google.api.http) = {
        get: "/auth/iam/roles"
        additional_bindings {
          get: "/auth/iam/{parent=organizations/*}/roles"
        }
        additional_bindings {
          get: "/auth/iam/{parent=tenants/*}/roles"
        }
      };
}

The parent can take the form organizations/<org_id> or tenants/<tenant_id> or it can be empty. I'd like the generated swagger definitions to match all three. For example:

GET /auth/iam/roles GET /auth/iam/organizations/<org_id>/roles GET /auth/iam/tenants/<tenant_id>/roles

The swagger generator currently only generates two paths:

GET /auth/iam/roles GET /auth/iam/{parent}/roles

{parent} only matches a single path parameter, and since the parent can include a slash you can't get a match.

What's the correct way of doing this?