Bug 176107 row.__rownum cannot be directly used as group key
Create a table that bind it to a data set. Insert a group. For the Group On field, click on the "..." button to edit the expression, and select from "Availble Column Bindings" | "Table" | "RowNum". This creates a Group On Expression "row.__rownum". The resulting report design cannot be run. It produces error: Column binding "row.__rownum" does not exist. To workaround this, one must create another binding on the table and set its expression to "row.__rownum", then use the new binding as group key. This should not have been necessary. The "__rownum" binding should be implicitly available in all contexts that have a data set. E.g., it should be usable directly as group key, sort key, and in conditional format expressions, etc. Attached is a sample report that produces the error.
data/org.eclipse.birt.data.tests/test/org/eclipse/birt/data/engine/binding/GroupOnRowTest.java
rowData += formatStr( "", expectedLen );;
				}
				for ( int j = groupCount; j < beArray.length; j++ )
				{
					String value = ri.getValue( beArray[j] ).toString( );
					rowData += formatStr( value, expectedLen );
				}
			}
			sBuffer.append( rowData );
			sBuffer.append( "\n" );
		}
		return new String( sBuffer );
	}
	
	/**
	 * Test feature of group on day
	 * 
	 * @throws Exception
	 */
	public void testGroupOnDay(  ) throws Exception
	{
		calendar.set( 2005, 0, 1, 10, 0, 0 );
		groupOnDay( calendar.getTime( ));
	}
	/**
	 * Test feature of group on day
	 * 
	 * @throws Exception
	 */
	public void testGroupOnDay1(  ) throws Exception