RFR: 8089398: [ChoiceBox, ComboBox] throws NPE on setting value on null selectionModel [v6]

[Ajit Ghaisas]

On Tue, 27 Jul 2021 12:41:00 GMT, Marius Hanl <mhanl at openjdk.org> wrote:

>> This PR fixes multiple NPEs in Choice-and ComboBox, when the selection model is null.
>> 
>> ChoiceBox: 
>> - Null check in **valueProperty()** listener
>> 
>> ComboBox:
>> - Null check in **editableProperty()** listener
>> - Null check in **valueProperty()** listener
>> - Null check in **ComboBoxListViewSkin#updateValue()**
>> - Null check in **ComboBoxListViewSkin#layoutChildren()**
>> - 2x Null check in **ComboBoxListViewSkin#createListView()**
>> 
>> ~~The tests checks, that no NPE is printed to the console.
>> Some checks, that the set value is still displayed (either in the ComboBox button cell or the ChoiceBox display label)~~
>
> Marius Hanl has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fixed another NPE on skin creation when the cbx selection model is null

Marked as reviewed by aghaisas (Reviewer).

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PR: https://git.openjdk.java.net/jfx/pull/557