IDEA-193969 Project leak via UIUtil$JBHtmlEditorKit

platform/util/src/com/intellij/util/ui/UIUtil.java

@@ -2884,13 +2884,8 @@ public class UIUtil {
     @Override
     public Document createDefaultDocument() {
       StyleSheet styles = getStyleSheet();
-      StyleSheet ss = new StyleSheet() {
-        @Override
-        protected int getCompressionThreshold() {
-          return -1;
-        }
-      };
-
+      // static class instead anonymous for exclude $this [memory leak]
+      StyleSheet ss = new StyleSheetCompressionThreshold();
       ss.addStyleSheet(styles);
 
       HTMLDocument doc = new HTMLDocument(ss);
@@ -2966,6 +2961,13 @@ public class UIUtil {
     }
   }
 
+  private static class StyleSheetCompressionThreshold extends StyleSheet {
+    @Override
+    protected int getCompressionThreshold() {
+      return -1;
+    }
+  }
+
   // Workaround for https://bugs.openjdk.java.net/browse/JDK-8202529
   private static class MouseExitSupportLinkController extends HTMLEditorKit.LinkController {
     @Override