Bug 122254 Not Like operator is missing in the Filter tab of Data Set window
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/parser/EngineIRVisitor.java
else if ( ( defaultStr != null ) && defaultStr.length( ) > 0 )
		{
			rule.setTestExpression( defaultStr );
		}
		else
		{
			
			return null;
		}
		ConditionalExpression condExpr = new ConditionalExpression( rule
				.getTestExpression( ),
				toDteFilterOperator( rule.getOperator( ) ), rule.getValue1( ),
				rule.getValue2( ) );
		rule.setConditionExpr( condExpr );
		return rule;
	}
	/**
	 * Checks if a given style is in report's style list, if not, assign a
	 * unique name to it and then add it to the style list.
	 * 
	 * @param style
	 *            The <code>StyleDeclaration</code> object.
	 * @return the name of the style.
	 */
	private String assignStyleName( StyleDeclaration style )
	{
		if ( style == null || style.isEmpty( ) )
		{
			return null;
		}