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
* 
	 * @return the second operand expression
	 */
	public String getValue2( )
	{
		return (String) getProperty( null, VALUE2_MEMBER );
	}
	/**
	 * Set expression for the second operand.
	 * 
	 * @param value
	 *            the second operand expression.
	 */
	public void setValue2( String value )
	{
		setProperty( VALUE2_MEMBER, value );
	}
	/**
	 * sets the test expression for the rule.
	 * 
	 * @param expression
	 *            the expression value
	 * 
	 */
	public void setTestExpression( String expression )
	{
		setProperty( TEST_EXPR_MEMBER, expression );
	}
	/**
	 * gets the test expression value of this rule.