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 operator
	 */
	public String getOperator( )
	{
		return (String) getProperty( null, OPERATOR_MEMBER );
	}
	/**
	 * Sets the operator. The allowed values are defined in
	 * {@link org.eclipse.birt.report.model.api.elements.DesignChoiceConstants},
	 * and they are:
	 * <ul>
	 * <li>MAP_OPERATOR_EQ
	 * <li>MAP_OPERATOR_NE
	 * <li>MAP_OPERATOR_LT
	 * <li>MAP_OPERATOR_LE
	 * <li>MAP_OPERATOR_GE
	 * <li>MAP_OPERATOR_GT
	 * <li>MAP_OPERATOR_BETWEEN
	 * <li>MAP_OPERATOR_NOT_BETWEEN
	 * <li>MAP_OPERATOR_NULL
	 * <li>MAP_OPERATOR_NOT_NULL
	 * <li>MAP_OPERATOR_TRUE
	 * <li>MAP_OPERATOR_FALSE
	 * <li>MAP_OPERATOR_LIKE
	 * <li>MAP_OPERATOR_ANY
	 * </ul>
	 * 
	 * @param operator
	 *            the operator to set