Describe the bug
If the value of the combo box is changed to one from the value list, the control is focused out and then the value list is opened again, the value list contains only the selected value.

To Reproduce
Steps to reproduce the behavior:

1. Run the JSON Forms Angular Material Playground from: https://github.com/eclipsesource/jsonforms-angular-material-playground, based on JSON Forms version 2.0.12
2. In any of the orders (e.g. Sirius Cybernetics Corp), click on the Status combo and change its value (e.g. to planned). Notice how several values are shown in the value list, that you can select from.
3. Now click on the Selectcombo again
4. The value list has only one value and it's the one that you selected before (planned)

Expected behavior
The value list should always contain all available options, unless the user explicitly wants to filter it by typing something in the selection box. On focus out, the filter should be cleared.

Browser (please complete the following information):

• Browser: Chrome
• Version: 70.0.3538.77 (Official Build) (64-bit)

Used Setup (please complete the following information):

• Framework: angular
• RendererSet: material