public TableRef isNull(String attributeName){
		filters.add(new Filter(StorageFilter.NULL, attributeName, null, null));
		return this;
	}
public TableRef isNull ( String attributeName ) { filters . add ( new Filter ( StorageFilter . NULL , attributeName , null , null ) ) ; return this ; }
Applies a filter to the table. When fetched, it will return the null values.

<pre>
StorageRef storage = new StorageRef("your_app_key", "your_token");

TableRef tableRef = storage.table("your_table");

// Retrieve all items where their "itemProperty" value is null
tableRef.isNull("itemProperty").getItems(new OnItemSnapshot() {
&#064;Override
public void run(ItemSnapshot itemSnapshot) {
if (itemSnapshot != null) {
Log.d("TableRef", "Item retrieved: " + itemSnapshot.val());
}
}
}, new OnError() {
&#064;Override
public void run(Integer code, String errorMessage) {
Log.e("TableRef", "Error retrieving items: " + errorMessage);
}
});

</pre>

@param attributeName
The name of the property to filter.
@return Current table reference