diff --git a/kdoc/src/main/kotlin/org/jetbrains/kotlin/doc/JavadocStyleHtmlDoclet.kt b/kdoc/src/main/kotlin/org/jetbrains/kotlin/doc/JavadocStyleHtmlDoclet.kt
index 1beb4cf3375..fcdd37103f1 100644
--- a/kdoc/src/main/kotlin/org/jetbrains/kotlin/doc/JavadocStyleHtmlDoclet.kt
+++ b/kdoc/src/main/kotlin/org/jetbrains/kotlin/doc/JavadocStyleHtmlDoclet.kt
@@ -51,8 +51,8 @@ class JavadocStyleHtmlDoclet() : Doclet {
             classes.addAll(pmap.keySet())
             for (c in classes) {
                 if (c != null) {
-                    val functions = map.get(c).notNull()
-                    val properties = pmap.get(c).notNull()
+                    val functions = map.get(c).orEmpty()
+                    val properties = pmap.get(c).orEmpty()
                     run("${p.nameAsPath}/${c.nameAsPath}-extensions.html",
                     ClassExtensionsTemplate(model, p, c, functions, properties))
                 }
diff --git a/kdoc/src/main/kotlin/org/jetbrains/kotlin/doc/templates/KDocTemplate.kt b/kdoc/src/main/kotlin/org/jetbrains/kotlin/doc/templates/KDocTemplate.kt
index ff9ae34c4a3..a5da59318e6 100644
--- a/kdoc/src/main/kotlin/org/jetbrains/kotlin/doc/templates/KDocTemplate.kt
+++ b/kdoc/src/main/kotlin/org/jetbrains/kotlin/doc/templates/KDocTemplate.kt
@@ -78,7 +78,7 @@ abstract class KDocTemplate() : TextTemplate() {
             if ((cname.startsWith("jet.Function") || cname.startsWith("jet.ExtensionFunction")) && arguments.notEmpty()) {
                 val rt = arguments.last()
                 // TODO use drop()
-                val rest = arguments.subList(0, arguments.size - 1).notNull()
+                val rest = arguments.subList(0, arguments.size - 1).orEmpty()
                 "${typeArguments(rest, "(", ")", "()")}&nbsp;<A HREF=\"${href(c)}\" title=\"${c.kind} in ${c.packageName}\">-&gt;</a>&nbsp;${link(rt)}"
             } else if (cname.startsWith("jet.Tuple")) {
                 if (arguments.isEmpty()) {
diff --git a/kdoc/src/main/kotlin/org/jetbrains/kotlin/model/KotlinModel.kt b/kdoc/src/main/kotlin/org/jetbrains/kotlin/model/KotlinModel.kt
index fc8353e2798..c7808e5e4ff 100644
--- a/kdoc/src/main/kotlin/org/jetbrains/kotlin/model/KotlinModel.kt
+++ b/kdoc/src/main/kotlin/org/jetbrains/kotlin/model/KotlinModel.kt
@@ -45,7 +45,7 @@ fun inheritedExtensionFunctions(functions: Collection<KFunction>): Map<KClass, S
     // for each class, lets walk its base classes and add any other extension functions from base classes
     val answer = TreeMap<KClass, SortedSet<KFunction>>()
     for (c in map.keySet()) {
-        val allFunctions = map.get(c).notNull().toSortedSet()
+        val allFunctions = map.get(c).orEmpty().toSortedSet()
         answer.put(c, allFunctions)
         val des = c.descendants()
         for (b in des) {
@@ -73,7 +73,7 @@ fun inheritedExtensionProperties(properties: Collection<KProperty>): Map<KClass,
     // for each class, lets walk its base classes and add any other extension properties from base classes
     val answer = TreeMap<KClass, SortedSet<KProperty>>()
     for (c in map.keySet()) {
-        val allProperties = map.get(c).notNull().toSortedSet()
+        val allProperties = map.get(c).orEmpty().toSortedSet()
         answer.put(c, allProperties)
         val des = c.descendants()
         for (b in des) {
diff --git a/stdlib/ktSrc/JavaUtil.kt b/stdlib/ktSrc/JavaUtil.kt
index cdad00345e8..9fb67df26f2 100644
--- a/stdlib/ktSrc/JavaUtil.kt
+++ b/stdlib/ktSrc/JavaUtil.kt
@@ -54,12 +54,12 @@ inline fun <in T: java.lang.Comparable<T>> List<T>.sort(comparator: java.util.Co
   return this
 }
 
-/** Converts the nullable List into an empty List if its null */
-inline fun <T> java.util.List<T>?.notNull() : java.util.List<T>
+/** Returns the List if its not null otherwise returns the empty list */
+inline fun <T> java.util.List<T>?.orEmpty() : java.util.List<T>
     = if (this != null) this else Collections.EMPTY_LIST as java.util.List<T>
 
-/** Converts the nullable Set into an empty Set if its null */
-inline fun <T> java.util.Set<T>?.notNull() : java.util.Set<T>
+/** Returns the Set if its not null otherwise returns the empty set */
+inline fun <T> java.util.Set<T>?.orEmpty() : java.util.Set<T>
     = if (this != null) this else Collections.EMPTY_SET as java.util.Set<T>
 
 /**
@@ -99,7 +99,7 @@ val <T> List<T>.last : T?
 /** Returns true if the collection is not empty */
 inline fun <T> java.util.Collection<T>.notEmpty() : Boolean = !this.isEmpty()
 
-/** Converts the nullable collection into an empty collection if its null */
-inline fun <T> java.util.Collection<T>?.notNull() : Collection<T>
+/** Returns the Collection if its not null otherwise it returns the empty list */
+inline fun <T> java.util.Collection<T>?.orEmpty() : Collection<T>
     = if (this != null) this else Collections.EMPTY_LIST as Collection<T>
 
diff --git a/stdlib/ktSrc/JavaUtilMap.kt b/stdlib/ktSrc/JavaUtilMap.kt
index 7768c4cc50f..4ef04bddf6f 100644
--- a/stdlib/ktSrc/JavaUtilMap.kt
+++ b/stdlib/ktSrc/JavaUtilMap.kt
@@ -20,8 +20,8 @@ val JMap<*,*>.empty : Boolean
 /** Provides [] access to maps */
 fun <K, V> JMap<K, V>.set(key : K, value : V) = this.put(key, value)
 
-/** Converts the nullable Map into an empty Map if its null */
-inline fun <K,V> java.util.Map<K,V>?.notNull() : java.util.Map<K,V>
+/** Returns the Mao if its not null otherwise it returns the empty Map */
+inline fun <K,V> java.util.Map<K,V>?.orEmpty() : java.util.Map<K,V>
     = if (this != null) this else Collections.EMPTY_MAP as java.util.Map<K,V>