How to update annotation value in Kotlin

Hi
I wonder the properly way for update text value of annotation value argument?

At first I wrote this code:

    fun updateAnnotationValueText(project: Project, annotation: KtAnnotationEntry, argumentName: String, newValueText: String) {
        val valueArgExpression = annotation.valueArguments.find { it.getArgumentName()?.asName?.identifier == argumentName }?.getArgumentExpression()
        WriteCommandAction.runWriteCommandAction(project) {
            val newAttributeExpression = JavaPsiFacade.getElementFactory(project).createExpressionFromText(newValueText, valueArgExpression)
            valueArgExpression?.replace(newAttributeExpression)
        }
    }

It works. 
But if i try to change this value next time without editing/changing any in file, `.getArgumentExpression()` returns null
Because the argument expression type is PsiLiteralExpression, bun not KtStringTemplateExpression as at first time

Now i changed getting valueArgExpression to

val valueArgument = (annotation.valueArguments.find { it.getArgumentName()?.asName?.identifier == argumentName }as KtValueArgument).children.find { it is KtExpression || it is PsiExpression }

But it seams i miss something and there is more properly way.
Thanks in advance.