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
set( Calendar.MILLISECOND, 0 );
			set( Calendar.SECOND, 0 );
			set( Calendar.MINUTE, 0 );
		}
		else if ( iUnit == MINUTE )
		{
			set( Calendar.MILLISECOND, 0 );
			set( Calendar.SECOND, 0 );
		}
		else if ( iUnit == SECOND )
		{
			set( Calendar.MILLISECOND, 0 );
		}
	}
	/**
	 * Parses a value formatted as MM-dd-yyyy HH:mm:ss and attempts to create an
	 * instance of this object
	 * 
	 * @param sDateTimeValue
	 *            The value to be parsed
	 * @return An instance of the datetime value created
	 */
	public static CDateTime parse( String sDateTimeValue )
	{
		try
		{
			return new CDateTime( _sdf.parse( sDateTimeValue ) );
		}
		catch ( Exception ex )
		{