Bug 152430 Key can modify to empty string
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/DataSetParameterHandle.java
{
			super( structHandle, member );
			paramHandle = (DataSetParameterHandle) structHandle;
		}
		/*
		 * (non-Javadoc)
		 * 
		 * @see org.eclipse.birt.report.model.api.SimpleValueHandle#setValue(java.lang.Object)
		 */
		public void setValue( Object value ) throws SemanticException
		{
			String oldName = this.getStringValue( );
			getModule( ).getActivityStack( ).startTrans( );
			try
			{
				super.setValue( value );
			}
			catch ( PropertyValueException e )
			{
				getModule( ).getActivityStack( ).rollback( );
				throw e;
			}
			
			DataSetHandle.DataSetParametersPropertyHandle propHandle = (DataSetHandle.DataSetParametersPropertyHandle) getElementHandle( )
					.getPropertyHandle( getPropertyDefn( ).getName( ) );
			propHandle.updateParamBindings( oldName, value.toString( ) );
			getModule( ).getActivityStack( ).commit( );
		}
	}
}