Image Slider save() drops extra classes (customClassName false)

Plugin: Slider Block for Gutenberg Gutenslider by GSlider (gslider-blocks) 1.1.7
Block: gslider-blocks/image-slider
WordPress: 7.0.4

The Image Slider wrapper does not behave like a native Gutenberg block, so extra classes never appear on the saved frontend HTML.

build/blocks/image-slider/block.json sets:

"supports": {
  "html": false,
  "anchor": false,
  "customClassName": false
}

And save() hard-codes its own className instead of merging extra classes:

useBlockProps.save({
  className: gslider-image-slider-wrapper ${blockId} ${navPosType} ${navPos} ${showPagination ? "has-pagination" : ""}
})

Result: Pattern CSS (and anything else that uses blocks.getSaveContent.extraProps / Additional CSS class) can store a class on the block in the editor, and can even print the compiled CSS in the head, but the wrapper never gets that class.

Example: Pattern CSS id pcss-z6posv2d compiled to:

.pcss-z6posv2d{margin-bottom:0!important}

Saved markup:

<div class="wp-block-gslider-blocks-image-slider alignfull gslider-image-slider-wrapper gslider-image-slider-73b76d4c inside center has-pagination">

No pcss-z6posv2d. The editor still looks styled because Pattern CSS can paint the edit wrapper via getEditWrapperProps. The frontend does not.

Core Group (and other native blocks with the default customClassName: true) get the class on the saved <div> as expected.

Ask: set customClassName to true (or omit it), and merge extra className from useBlockProps.save() instead of replacing it. Same root cause as the has-pagination class always being present — className is treated as a private template, not a Gutenberg merge.