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/computation/DataSetIterator.java
{
	private double[] da = null;
	private Double[] dda = null;
	private Calendar[] ca = null;
	private long[] la = null;
	private String[] sa = null;
	private Collection co = null;
	private int iDataType = IConstants.UNDEFINED;
	private int iContentType = IConstants.UNDEFINED;
	private int iCursor = 0;
	private Iterator it = null;
	private int iRowCount = 0;
	private Calendar cReused = null;
	private Object[] oa = null;