Guided Decision Tables: Construction of DRL for "otherwise" values includes empty String

Description of problem:

Columns with "otherwise" cells generate DRL including the "otherwise" cell; manifesting itself as an empty String in the DRL. For example 'Person( name not in ( "Mike", "Mark", "" ) )'. This is caused by marshalling of the Decision Table model from client to server where the default constructor for DTCellValue52 sets the cell's value to an empty String.

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

6.4.0.Final (Community); 6.3.x (Product)

How reproducible:

Steps to Reproduce:
1. Create a Guided Decision Table
2. Add a Condition column for a String field
3. Set operator to "=="
4. Add at least 2 rows
5. Set the cell of the column, row 1 to "a"
6. Set the cell of the column, row 2 to <otherwise>
7. View source

Actual results:

DRL like 'Person( name not in ("a", "") )' is generated.

The empty String is erroneous.

Expected results:

DRL like 'Person( name not in ("a") )' is generated.