containerCssClass setting has no effect with Select2 4.1.0 - should map to selectionCssClass

[matutet]

Problem

Settings.setContainerCssClass("my-class") has no effect on the rendered DOM. The class is not applied to any element.

Root cause

In Settings.toJson() (line 124), the setting is serialized as:

Json.writeObject(writer, "containerCssClass", containerCssClass);

But Select2 4.1.0 (bundled in wicketstuff-select2 9.22.0) removed containerCssClass. The equivalent option is selectionCssClass, which applies the class to the .select2-selection element.

Reference: https://select2.org/configuration/options-api

Verified behavior

• dropdownCssClass → works correctly (applied to .select2-dropdown)
• containerCssClass → ignored by Select2 4.1.0 JS (no element receives the class)
• Changing the JSON key from "containerCssClass" to "selectionCssClass" in Settings.toJson() fixes the issue: the class is applied to .select2-selection

Suggested fix

In Settings.java, line 124, change:

Json.writeObject(writer, "containerCssClass", containerCssClass);

to:

Json.writeObject(writer, "selectionCssClass", containerCssClass);

The Java API (setContainerCssClass/getContainerCssClass) can remain unchanged for backwards compatibility, or be renamed to setSelectionCssClass with the old method deprecated.

Environment

• wicketstuff-select2: 9.22.0
• Select2 JS bundled: 4.1.0-rc.0
• Wicket: 9.22.0

[solomax]

Hello @matutet,

Could you please check fix? if everything is OK I'll cherry-pick it to 9.x :)

[matutet]

Thanks for the quick fix! We've verified the same change on our side (Wicket 9.22.0 + Select2 4.1.0-rc.0) and it works correctly — the class is now applied to .select2-selection as expected.

The backwards-compatible deprecation of the old methods is a nice touch.

We'd appreciate the cherry-pick to 9.x whenever you get a chance. Thanks again!

[solomax]

Thanks for double-checking! :))