[birt-dev]CheckIn: Fix Bugzilla Bug --- 189078 Exception when click Expo

["Wei Yan" <wyan@xxxxxxxxxxx>]

Title: [birt-dev]CheckIn: Fix Bugzilla Bug --- 189078 Exception when click Export Data in report with xtab.[1102]

- Summary:

- Bugzilla Bug (s) Resolved:
189078 Exception when click Export Data in report with xtab.[1102]

- Description:
        1. DataExtract doesn't support XTAB in 2.2, so return NULL for the XTAB instance.

- Tests Description  :
        Manual Test

- Notes to Build Team:
        check into 2.2rc2

- Notes to Developers:

- Notes to QA:  
 
- Notes to Documentation:  

- Files Edited:
cvs ci -m "189078: return null for cube query" -l
"/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/DataExtractionTaskV1.java"


- Files Added:

- Files Deleted

-Wei Yan