Add a whitespace PsiElement after a bracket

Hi,

I have a PHP array like this:

return [
    'invokables' => [
        
    ],
];

The [] is a ArrayCreationExpression PSI.

I want to add a key inside and it's works

if (psiElement is ArrayCreationExpression) {
    val arrayKey = psiElement.addAfter(PhpPsiElementFactory.createFromText(project, ClassConstantReference::class.java,"$namespace::class")!!, psiElement.firstChild)
    if (!invokableFactory) {
        arrayKey.add(PhpPsiElementFactory.createFromText(project, LeafPsiElement::class.java, "=>")!!)
        arrayKey.add(PhpPsiElementFactory.createFromText(project, ClassConstantReference::class.java, namespace + "Factory::class")!!)
    }
    arrayKey.add(comma)

}

The output is:

return [
    'invokables' => [Something\Here\And\Foo::class

    ],
];

I read we don't need to add whitespace because the API does that for us but it's not working and when I try to add a whitespace with the text "\n" it's not working either.

How to add a new line after the open bracket?