message: scaffolder-backend: validate dry-run template input
diff: @@ -28,6 +28,7 @@ import { ScmIntegrations } from '@backstage/integration';
  import {
  TemplateEntityV1beta3,
  TaskSpec,
  + templateEntityV1beta3Validator,
  } from '@backstage/plugin-scaffolder-common';
  import express from 'express';
  import Router from 'express-promise-router';
  @@ -336,6 +337,10 @@ export async function createRouter(
  })
  .post('/v2/dry-run', async (req, res) => {
  const template = req.body.template as TemplateEntityV1beta3;
  + if (!(await templateEntityV1beta3Validator.check(template))) {
  + throw new InputError('Input template is not a template');
  + }
  +
  const values = req.body.values;
  const token = getBearerToken(req.headers.authorization);
  const content = req.body.content as {
  