Setting an empty filter on a filtered Number or DateTime grid column doesn't work

[matanasov]

Bug report

Setting an empty filter does nothing

Reproduction of the problem

1. Open the Demo
2. Filter any Number or DateTime column
3. Open the filter menu of the same column and clear the filter value.
4. Click the "filter" button without inputting a value - visually no filtering is set, but the grid is still filtered:

Current behavior

The grid will now persist the applied filters

Expected/desired behavior

The grid should reset, clearing the current column filter or apply empty filter

Environment

• Kendo UI version: 2018.2.620
• Browser: [all ]

This is misleading to the user.

In the case above we have Is equal to as an operator and we should consider it - either apply it explicitly and return empty collection (which will be similar to Is Empty\Is Null) or clear the filter as with String columns.
Another option would be to have the Filter button disabled when the filter values are empty and enabled it only when some values as entered.