Bug 202254 Exception is thrown when category values are null and type of X axis is set to DateTime
chart/org.eclipse.birt.chart.engine/src/org/eclipse/birt/chart/util/CDateTime.java
}
	/**
	 * Returns the year associated with this instance
	 * 
	 * @return The year associated with this instance
	 */
	public final int getYear( )
	{
		return get( Calendar.YEAR );
	}
	/**
	 * Returns the month (0-based) associated with this instance
	 * 
	 * @return The month associated with this instance
	 */
	public final int getMonth( )
	{
		return get( Calendar.MONTH );
	}
	/**
	 * Returns the day of the month associated with this instance
	 * 
	 * @return The day of the month associated with this instance
	 */
	public final int getDay( )
	{
		return get( Calendar.DATE );
	}
	/**
	 * Returns the hour (military) associated with this instance