Bug 211839 String grouping unit type needs to support interval range.
Build ID: I20071101-2000 As Chart has supported, the String grouping unit type can be set interval range, the interval range means that the string group will base on row count distinction. For instance, let's say we have a,b,c,d,e,f,g , and set interval range to 2, the grouping result should be a,c,e,g. Now it is a requirement that DtE support the grouping type.
data/org.eclipse.birt.data.tests/test/org/eclipse/birt/data/engine/binding/DataSetCacheTest.java
}
				for ( int j = groupCount; j < beArray.length; j++ )
				{
					String value = ri.getValue( beArray[j] ).toString( );
					rowData += formatStr( value, expectedLen );
				}
			}
			sBuffer.append( rowData );
			sBuffer.append( "\n" );
		}
		return new String( sBuffer );
	}
	/**
	 * Format string to specified length, if the length of input string is
	 * larger than expected length, then input string will be directly return
	 * without any format.
	 * 
	 * @param str
	 *            needs to be formatted string
	 * @param length
	 *            expected length
	 * @return formatted string
	 */
	private static String formatStr( String inputStr, int length )
	{
		if ( inputStr == null )
			return null;
		int inputLen = inputStr.length( );
		if ( inputLen >= length )
			return inputStr;