public operator inline fun <@kotlin.internal.OnlyInputTypes K, V> kotlin.collections.Map<out kotlin.String>.get(key: kotlin.String): ??? defined in kotlin.collections
显然,Kotlin无法理解Map中"value“字段的数据类型。另外,
元素访问器应该在不存在的键上返回null,但是相反。myMapOfThings["item3"]抛出java.util.NoSuchElementException: Key item3 is missing in the map.中为Map声明的* Returns the value corresponding to the given [key], or `null` if such a key is not presentin the <em