diff --git a/platform/lang-api/src/com/intellij/codeInsight/daemon/RelatedItemLineMarkerProvider.java b/platform/lang-api/src/com/intellij/codeInsight/daemon/RelatedItemLineMarkerProvider.java
index e78c7d51c392..d2c899a9e95f 100644
--- a/platform/lang-api/src/com/intellij/codeInsight/daemon/RelatedItemLineMarkerProvider.java
+++ b/platform/lang-api/src/com/intellij/codeInsight/daemon/RelatedItemLineMarkerProvider.java
@@ -40,8 +40,8 @@ public abstract class RelatedItemLineMarkerProvider extends LineMarkerProviderDe
     collectNavigationMarkers(elements, result, false);
   }
 
-  public void collectNavigationMarkers(List<PsiElement> elements,
-                                       Collection<? super RelatedItemLineMarkerInfo> result,
+  public void collectNavigationMarkers(@NotNull List<PsiElement> elements,
+                                       @NotNull Collection<? super RelatedItemLineMarkerInfo> result,
                                        boolean forNavigation) {
     //noinspection ForLoopReplaceableByForEach
     for (int i = 0, size = elements.size(); i < size; i++) {
@@ -56,7 +56,7 @@ public abstract class RelatedItemLineMarkerProvider extends LineMarkerProviderDe
     }
   }
 
-  protected void collectNavigationMarkers(@NotNull PsiElement element, Collection<? super RelatedItemLineMarkerInfo> result) {
+  protected void collectNavigationMarkers(@NotNull PsiElement element, @NotNull Collection<? super RelatedItemLineMarkerInfo> result) {
   }
 
   @Override
diff --git a/xml/dom-impl/src/com/intellij/codeInsight/navigation/NavigationGutterIconBuilder.java b/xml/dom-impl/src/com/intellij/codeInsight/navigation/NavigationGutterIconBuilder.java
index 2aec910544bd..841fa87f6c79 100644
--- a/xml/dom-impl/src/com/intellij/codeInsight/navigation/NavigationGutterIconBuilder.java
+++ b/xml/dom-impl/src/com/intellij/codeInsight/navigation/NavigationGutterIconBuilder.java
@@ -57,8 +57,8 @@ import java.util.*;
  */
 public class NavigationGutterIconBuilder<T> {
   @NonNls private static final String PATTERN = "&nbsp;&nbsp;&nbsp;&nbsp;{0}";
-  private static final NotNullFunction<PsiElement, Collection<? extends PsiElement>> DEFAULT_PSI_CONVERTOR =
-    element -> ContainerUtil.createMaybeSingletonList(element);
+  private static final NotNullFunction<PsiElement,Collection<? extends PsiElement>> DEFAULT_PSI_CONVERTOR =
+    ContainerUtil::createMaybeSingletonList;
 
   private final Icon myIcon;
   private final NotNullFunction<T, Collection<? extends PsiElement>> myConverter;
@@ -90,7 +90,7 @@ public class NavigationGutterIconBuilder<T> {
 
   protected NavigationGutterIconBuilder(@NotNull final Icon icon,
                                         @NotNull NotNullFunction<T, Collection<? extends PsiElement>> converter,
-                                        final @Nullable NotNullFunction<T, Collection<? extends GotoRelatedItem>> gotoRelatedItemProvider) {
+                                        @Nullable final NotNullFunction<T, Collection<? extends GotoRelatedItem>> gotoRelatedItemProvider) {
     myIcon = icon;
     myConverter = converter;
     myGotoRelatedItemProvider = gotoRelatedItemProvider;
@@ -110,7 +110,7 @@ public class NavigationGutterIconBuilder<T> {
   @NotNull
   public static <T> NavigationGutterIconBuilder<T> create(@NotNull final Icon icon,
                                                           @NotNull NotNullFunction<T, Collection<? extends PsiElement>> converter,
-                                                          final @Nullable NotNullFunction<T, Collection<? extends GotoRelatedItem>> gotoRelatedItemProvider) {
+                                                          @Nullable final NotNullFunction<T, Collection<? extends GotoRelatedItem>> gotoRelatedItemProvider) {
     return new NavigationGutterIconBuilder<>(icon, converter, gotoRelatedItemProvider);
   }
 
@@ -274,7 +274,7 @@ public class NavigationGutterIconBuilder<T> {
     }
 
     Computable<PsiElementListCellRenderer> renderer =
-      myCellRenderer == null ? () -> new DefaultPsiElementCellRenderer() : myCellRenderer;
+      myCellRenderer == null ? DefaultPsiElementCellRenderer::new : myCellRenderer;
     return new MyNavigationGutterIconRenderer(this, myAlignment, myIcon, myTooltipText, pointers, renderer, empty);
   }
 
@@ -334,13 +334,13 @@ public class NavigationGutterIconBuilder<T> {
     private final String myTooltipText;
     private final boolean myEmpty;
 
-    public MyNavigationGutterIconRenderer(@NotNull NavigationGutterIconBuilder builder,
-                                          final Alignment alignment,
-                                          final Icon icon,
-                                          @Nullable final String tooltipText,
-                                          @NotNull NotNullLazyValue<List<SmartPsiElementPointer>> pointers,
-                                          Computable<PsiElementListCellRenderer> cellRenderer,
-                                          boolean empty) {
+    MyNavigationGutterIconRenderer(@NotNull NavigationGutterIconBuilder builder,
+                                   final Alignment alignment,
+                                   final Icon icon,
+                                   @Nullable final String tooltipText,
+                                   @NotNull NotNullLazyValue<List<SmartPsiElementPointer>> pointers,
+                                   Computable<PsiElementListCellRenderer> cellRenderer,
+                                   boolean empty) {
       super(builder.myPopupTitle, builder.myEmptyText, cellRenderer, pointers);
       myAlignment = alignment;
       myIcon = icon;
diff --git a/xml/impl/src/com/intellij/html/HtmlLineMarkerProvider.java b/xml/impl/src/com/intellij/html/HtmlLineMarkerProvider.java
index a48e031e12b9..c176b4b11324 100644
--- a/xml/impl/src/com/intellij/html/HtmlLineMarkerProvider.java
+++ b/xml/impl/src/com/intellij/html/HtmlLineMarkerProvider.java
@@ -57,7 +57,8 @@ public class HtmlLineMarkerProvider implements LineMarkerProvider {
 
     if (!embeddedLanguagesLineMarkerProviders.containsKey(language)) {
       embeddedLanguagesLineMarkerProviders.put(language, markerProvider = LineMarkerProviders.INSTANCE.forLanguage(language));
-    } else {
+    }
+    else {
       markerProvider = embeddedLanguagesLineMarkerProviders.get(language);
     }
     return markerProvider;
@@ -81,12 +82,7 @@ public class HtmlLineMarkerProvider implements LineMarkerProvider {
 
         if (lineMarkerProvider != null) {
           if (embeddedLineMarkersWorkItems == null) embeddedLineMarkersWorkItems = new THashMap<>();
-          List<PsiElement> elementList = embeddedLineMarkersWorkItems.get(lineMarkerProvider);
-
-          if (elementList == null) {
-            elementList = new ArrayList<>(5);
-            embeddedLineMarkersWorkItems.put(lineMarkerProvider, elementList);
-          }
+          List<PsiElement> elementList = embeddedLineMarkersWorkItems.computeIfAbsent(lineMarkerProvider, k -> new ArrayList<>(5));
 
           elementList.add(element);
         }