Fix type nullability of a variable in an util method

Author: ArsenHD

utbot-framework/src/main/kotlin/org/utbot/framework/codegen/model/visitor/UtilMethods.kt

@@ -159,7 +159,7 @@ fun getFieldValue(language: CodegenLanguage): String =
         CodegenLanguage.KOTLIN -> {
             """
             private fun getFieldValue(any: kotlin.Any, fieldClassName: String, fieldName: String): kotlin.Any? {
-                val clazz: Class<*>? = Class.forName(fieldClassName)
+                val clazz: Class<*> = Class.forName(fieldClassName)
                 val field: java.lang.reflect.Field = clazz.getDeclaredField(fieldName)
                 
                 field.isAccessible = true