Saving a Theme Modification mobile device rule causes an HTTP Status 500 Error

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 7.0.X EE, Master
• Fix Version/s: 7.0.0 DXP FP26, 7.0.X EE, 7.0.4 CE GA5, 7.1.X, Master
• Component/s: Portal Services > Mobile Device Rules
• Labels:
  • liferay-digital-enterprise-70-sp5
  • liferay-fixpack-de-26-7010
• Branch Version/s:
  7.0.x
• Backported to Branch:
  Committed
• Fix Priority: 4
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/50517

Steps to Reproduce:

1. Navigate to Site > Configuration > Mobile Device Families
2. Add a Mobile Device Family
3. Select Configure Page for any site page
4. Navigate to the Advanced tab
5. Expand the Mobile Device Rules panel
6. Turn off the option for using the same rules as Public Pages
7. Add the Mobile Device Family
8. Click Manage Actions
9. Select Theme Modification
10. Choose any theme that's currently deployed (Ex. 1975)
11. Save
12. Close out of popup
13. Save

Expected result:
Configuration is saved with the new theme modification mobile device rule.

Actual result:
Error is thrown in browser.

Reproduced on:
Tomcat 8.0.32 + MySQL 5.6.
Portal master GIT ID: 61cc851371ad797d2e4f71e5dcd6fe841e6418e9
Portal ee-7.0.x GIT ID: e18a09ffdcc438ae7cb795a26ef3f5d977e33aef