Use the 'Remove curly braces' quick-fix to remove the redundant braces.
Examples:
fun redundant() {
val x = 4
val y = "${x}" // <== redundant
}
fun correctUsage() {
val x = "x"
val y = "${x.length}" // <== Ok
}
After the quick-fix is applied:
fun redundant() {
val x = 4
val y = "$x"
}
fun correctUsage() {
val x = "x" <== Updated
val y = "${x.length}"
}