message: fail when multiple colliding operations are present on the same path with the v2 composer
diff: @@ -177,6 +177,13 @@ export class NewComposer extends Transformer<AnyObject, AnyObject> {
  protected visitPath(metadata: AnyObject, target: AnyObject, nodes: Iterable<Node>) {
  for (const { key, pointer, children } of nodes) {
  + if (target[key] && !key.startsWith('x-ms')) {
  + // we're attempting to put another operation at the same path/method
  + // where there is one already.
  + // This is likely a case where a multi-api-version file is trying to
  + // go thru the composer, and this is not allowed.
  + throw new Error(`There are multiple operations defined for \n '${key}: ${metadata.path}'.\n\n You are probably trying to use an input with multiple API versions with an autorest V2 generator, and that will not work. `);
  + }
  this.visitOperation(metadata, this.getOrCreateObject(target, key, pointer), children);
  }
  }
  