Bug 206850 [Regression] Error pops up when select value for a map or highlight rule to group header row [0302]
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/elements/structures/StyleRule.java
protected String testExpression = null;
	/**
	 * 
	 */
	protected Boolean isDesignTime = null;
	/**
	 * Default constructor.
	 */
	public StyleRule( )
	{
	}
	/**
	 * Constructs the style rule with an operator and its operands.
	 * 
	 * @param op
	 *            the choice name for the operand
	 * @param v1
	 *            expression for the first operand
	 * @param v2
	 *            expression for the second operand
	 * @param testExpr
	 *            the expression to check
	 */
	public StyleRule( String op, String v1, String v2, String testExpr )
	{
		operator = op;
		value1 = new ArrayList( );
		value1.add( v1 );
		value2 = v2;
		testExpression = testExpr;