Bug 161219 Gantt chart with null datapoints fail to render
Create a dataset with two date columns, having some null date values Create a gantt chart Assign the dates to the gant series It fails to render and throw exception. Expected: null dates should be treated as: - 1 null date, 1 valid date ->one marker drawn, no line - 2 null dates -> skip rendering of datapoint If the decoration label is missing it should also not fail.
chart/org.eclipse.birt.chart.engine/src/org/eclipse/birt/chart/util/CDateTime.java
return iaUnitTypes[k]; 
					
				}
			}
		}
		
		return Calendar.YEAR;
	}
	/**
	 * Returns the number of days for a particular (month,year) combination
	 * 
	 * @param iMonth
	 *            The month (0-11) for which the day count is to be retrieved
	 * @param iYear
	 *            The year for which the day count is to be retrieved
	 * @return
	 */
	public static final int getMaximumDaysIn( int iMonth, int iYear )
	{
		CDateTime cdt = new CDateTime( );
		cdt.set( Calendar.YEAR, iYear );
		cdt.set( Calendar.MONTH, iMonth );
		return cdt.getActualMaximum( Calendar.DATE );
	}
	/**
	 * Returns the number of days for a particular year
	 * 
	 * @param iYear
	 *            The year for which the day count is to be retrieved
	 *