function enablePerBundleAddonCache(explicitValue) {
  // default is opt-out
  if (explicitValue !== null && explicitValue !== undefined) {
    process.env.EMBER_CLI_ADDON_INSTANCE_CACHING = explicitValue;
  } else {
    delete process.env.EMBER_CLI_ADDON_INSTANCE_CACHING;
  }
}
Tests for enabling and disabling per-bundle-addon-cache support