Replace map { ... }.filterNotNull() with mapNotNull { ... }

idea/idea-core/src/org/jetbrains/kotlin/idea/core/IterableTypesDetection.kt

@@ -48,8 +48,7 @@ public class IterableTypesDetection(
 
         private val typesWithExtensionIterator: Collection<KotlinType> = scope
                 .collectFunctions(iteratorName, NoLookupLocation.FROM_IDE)
-                .map { it.extensionReceiverParameter }
-                .filterNotNull()
+                .mapNotNull { it.extensionReceiverParameter }
                 .map { it.type }
 
         override fun isIterable(type: FuzzyType, loopVarType: KotlinType?): Boolean {

idea/idea-core/src/org/jetbrains/kotlin/idea/core/KotlinIndicesHelper.kt

@@ -189,8 +189,7 @@ public class KotlinIndicesHelper(
 
     public fun getJvmClassesByName(name: String): Collection<ClassDescriptor> {
         return PsiShortNamesCache.getInstance(project).getClassesByName(name, scope)
-                .map { it.resolveToDescriptor(resolutionFacade) }
-                .filterNotNull()
+                .mapNotNull { it.resolveToDescriptor(resolutionFacade) }
                 .filter(descriptorFilter)
                 .toSet()
     }

idea/idea-core/src/org/jetbrains/kotlin/idea/core/KotlinNameSuggester.kt

@@ -90,8 +90,7 @@ public object KotlinNameSuggester {
         val result = LinkedHashSet<String>()
 
         suggestNamesByExpressionOnly(collection, bindingContext, { true })
-                .map { StringUtil.unpluralize(it) }
-                .filterNotNull()
+                .mapNotNull { StringUtil.unpluralize(it) }
                 .mapTo(result) { suggestNameByName(it, validator) }
 
         result.addNamesByType(elementType, validator)

idea/idea-core/src/org/jetbrains/kotlin/idea/core/OptionalParametersHelper.kt

@@ -47,8 +47,7 @@ public object OptionalParametersHelper {
         val descriptor = resolvedCall.getResultingDescriptor()
 
         val parameterToDefaultValue = descriptor.getValueParameters()
-                .map { parameter -> defaultParameterValue(parameter, project)?.let { parameter to it } }
-                .filterNotNull()
+                .mapNotNull { parameter -> defaultParameterValue(parameter, project)?.let { parameter to it } }
                 .toMap()
         if (parameterToDefaultValue.isEmpty()) return emptyList()