[FIR] Cleanup ConeIntegerLiteralTypeImpl

compiler/fir/tree/src/org/jetbrains/kotlin/fir/types/ConeIntegerLiteralTypeImpl.kt

@@ -17,7 +17,11 @@ class ConeIntegerLiteralTypeImpl : ConeIntegerLiteralType {
     override val attributes: ConeAttributes
         get() = ConeAttributes.Empty
 
-    constructor(value: Long, isUnsigned: Boolean, nullability: ConeNullability = ConeNullability.NOT_NULL) : super(value, isUnsigned, nullability) {
+    constructor(
+        value: Long,
+        isUnsigned: Boolean,
+        nullability: ConeNullability = ConeNullability.NOT_NULL
+    ) : super(value, isUnsigned, nullability) {
         possibleTypes = mutableListOf()
 
         fun checkBoundsAndAddPossibleType(classId: ClassId, range: LongRange) {
@@ -75,7 +79,7 @@ class ConeIntegerLiteralTypeImpl : ConeIntegerLiteralType {
 
     @OptIn(ExperimentalUnsignedTypes::class)
     companion object {
-        fun createType(classId: ClassId): ConeClassLikeType {
+        private fun createType(classId: ClassId): ConeClassLikeType {
             return ConeClassLikeTypeImpl(ConeClassLikeLookupTagImpl(classId), emptyArray(), false)
         }
 
@@ -130,7 +134,7 @@ class ConeIntegerLiteralTypeImpl : ConeIntegerLiteralType {
             }
         }
 
-        private fun fold(left: ConeIntegerLiteralType, right: ConeIntegerLiteralType, mode: Mode): ConeIntegerLiteralType? {
+        private fun fold(left: ConeIntegerLiteralType, right: ConeIntegerLiteralType, mode: Mode): ConeIntegerLiteralType {
             val possibleTypes = when (mode) {
                 Mode.COMMON_SUPER_TYPE -> left.possibleTypes intersect right.possibleTypes
                 Mode.INTERSECTION_TYPE -> left.possibleTypes union right.possibleTypes