Description of problem:
Opening rule that modifies facts on RHS results with error dialog:

Unable to complete your request. The following exception occurred: java.lang.NoClassDefFoundError:org/apache/commons/lang/StringUtils.

The editor content is not loaded. Fact modification can be for example:

applicant.setName("name");

Version-Release number of selected component (if applicable):
6.0.1.CR2

How reproducible:
always

Steps to Reproduce:
1. Open any guided rule in mortgages (e.g. Underage)
OR
1. Create new rule
2. Insert new fact and set one of its fields
3. Save the rule, close and reopen

Actual results:
Error dialog with java.lang.NoClassDefFoundError:org/apache/commons/lang/StringUtils.

Expected results:
No error.

Additional info: