Use NoSuchElementException instead of KeyMissingException. Deprecate KeyMissingException.

libraries/stdlib/src/kotlin/collections/MapWithDefault.kt

@@ -1,26 +1,20 @@
 package kotlin
 
+import java.util.*
 import kotlin.platform.platformName
 
-
-/**
- * Exception thrown when the map does not contain the corresponding key.
- */
-public class KeyMissingException(message: String): RuntimeException(message)
-
-
 /**
  * Returns the value for the given key, or the implicit default value for this map.
- * By default no implicit value is provided for maps and a [KeyMissingException] is thrown.
+ * By default no implicit value is provided for maps and a [NoSuchElementException] is thrown.
  * To create a map with implicit default value use [Map.withDefault] method.
  *
- * @throws KeyMissingException when the map doesn't contain value for the specified key and no implicit default was provided for that map.
+ * @throws NoSuchElementException when the map doesn't contain value for the specified key and no implicit default was provided for that map.
  */
 public fun <K, V> Map<K, V>.getOrImplicitDefault(key: K): V {
     if (this is MapWithDefault)
         return this.getOrImplicitDefault(key)
 
-    return getOrElse(key, { throw KeyMissingException("Key $key is missing in the map.") })
+    return getOrElse(key, { throw NoSuchElementException("Key $key is missing in the map.") })
 }
 
 /**

libraries/stdlib/src/kotlin/properties/Delegation.kt

@@ -1,5 +1,7 @@
 package kotlin.properties
 
+import java.util.NoSuchElementException
+
 
 /**
  * Standard property delegates.
@@ -177,6 +179,16 @@ private class BlockingLazyVal<T>(lock: Any?, private val initializer: () -> T) :
     }
 }
 
+/**
+ * Exception thrown by the default implementation of property delegates which store values in a map
+ * when the map does not contain the corresponding key.
+ */
+deprecated("Do not throw or catch this exception, use NoSuchElementException instead.")
+public class KeyMissingException
+    deprecated("Throw NoSuchElementException instead.", ReplaceWith("NoSuchElementException(message)"))
+    constructor(message: String): NoSuchElementException(message)
+
+
 /**
  * Implements the core logic for a property delegate that stores property values in a map.
  * @param T the type of the object that owns the delegated property.

libraries/stdlib/src/kotlin/properties/MapAccessors.kt

@@ -1,6 +1,7 @@
 package kotlin.properties
 
 import java.io.Serializable
+import java.util.NoSuchElementException
 import kotlin.platform.platformName
 
 // extensions for Map and MutableMap
@@ -11,7 +12,7 @@ import kotlin.platform.platformName
  * @param property the metadata for the property, used to get the name of property and lookup the value corresponding to this name in the map.
  * @return the property value.
  *
- * @throws KeyMissingException when the map doesn't contain value for the property name and doesn't provide an implicit default (see [Map.withDefault]).
+ * @throws NoSuchElementException when the map doesn't contain value for the property name and doesn't provide an implicit default (see [Map.withDefault]).
  */
 public fun <V> Map<in String, *>.get(thisRef: Any?, property: PropertyMetadata): V = getOrImplicitDefault(property.name) as V
 
@@ -21,7 +22,7 @@ public fun <V> Map<in String, *>.get(thisRef: Any?, property: PropertyMetadata):
  * @param property the metadata for the property, used to get the name of property and lookup the value corresponding to this name in the map.
  * @return the property value.
  *
- * @throws KeyMissingException when the map doesn't contain value for the property name and doesn't provide an implicit default (see [Map.withDefault]).
+ * @throws NoSuchElementException when the map doesn't contain value for the property name and doesn't provide an implicit default (see [Map.withDefault]).
  */
 platformName("getVar")
 public fun <V> MutableMap<in String, in V>.get(thisRef: Any?, property: PropertyMetadata): V = getOrImplicitDefault(property.name) as V