Bug 159247 Implement toString() in class StringFormatValue, NumberFormatValue and DateTimeFormatValue
Engine need the implementation of toString() method in class StringFormatValue, NumberFormatValue and DateTimeFormatValue.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/elements/structures/FormatValue.java
* Sets the variable name.
	 * 
	 * @param name
	 *            the name to set
	 */
	public void setCategory( String name )
	{
		setProperty( CATEGORY_MEMBER, name );
	}
	/**
	 * Returns the variable value.
	 * 
	 * @return the variable value
	 */
	public String getPattern( )
	{
		return (String) getProperty( null, PATTERN_MEMBER );
	}
	/**
	 * Sets the variable value.
	 * 
	 * @param value
	 *            the value to set
	 */
	public void setPattern( String value )
	{
		setProperty( PATTERN_MEMBER, value );
	}
}