[UnescapedEntity] Ignore JavaDoc using Markdown syntax

core/src/main/java/com/google/errorprone/bugpatterns/javadoc/UnescapedEntity.java

@@ -36,6 +36,7 @@
 import com.google.errorprone.bugpatterns.BugChecker.VariableTreeMatcher;
 import com.google.errorprone.fixes.SuggestedFix;
 import com.google.errorprone.matchers.Description;
+import com.google.errorprone.util.ErrorProneComment.ErrorProneCommentStyle;
 import com.sun.source.doctree.DocTree;
 import com.sun.source.doctree.EndElementTree;
 import com.sun.source.doctree.ErroneousTree;
@@ -109,9 +110,13 @@ private Description handle(@Nullable DocTreePath path, VisitorState state) {
     if (path == null) {
       return NO_MATCH;
     }
+    Comment comment = ((DCDocComment) path.getDocComment()).comment;
+    // javac's markdown javadoc parser doesn't produce ErroneousTree for <, >, or &.
+    if (ErrorProneCommentStyle.from(comment.getStyle()) == ErrorProneCommentStyle.JAVADOC_LINE) {
+      return NO_MATCH;
+    }
     RangesFinder rangesFinder = new RangesFinder(state);
     rangesFinder.scan(path, null);
-    Comment comment = ((DCDocComment) path.getDocComment()).comment;
     Matcher matcher = GENERIC_PATTERN.matcher(comment.getText());
     RangeSet<Integer> generics = TreeRangeSet.create();
     while (matcher.find()) {

core/src/test/java/com/google/errorprone/bugpatterns/javadoc/UnescapedEntityTest.java

@@ -332,6 +332,48 @@ interface Test {}
         .doTest();
   }
 
+  @Test
+  public void markdownJavadoc_ampersand() {
+    assume().that(Runtime.version().feature()).isAtLeast(23);
+    helper
+        .addSourceLines(
+            "Test.java",
+            """
+            /// Foo & bar
+            interface Test {}
+            """)
+        .doTest();
+  }
+
+  @Test
+  public void markdownJavadoc_htmlTags() {
+    assume().that(Runtime.version().feature()).isAtLeast(23);
+    helper
+        .addSourceLines(
+            "Test.java",
+            """
+            /// <em>important</em> stuff
+            interface Test {}
+            """)
+        .doTest();
+  }
+
+  @Test
+  public void markdownJavadoc_codeBlock() {
+    assume().that(Runtime.version().feature()).isAtLeast(23);
+    helper
+        .addSourceLines(
+            "Test.java",
+            """
+            /// Example:
+            /// ```
+            /// List<Foo> list = new ArrayList<>();
+            /// ```
+            interface Test {}
+            """)
+        .doTest();
+  }
+
   @Test
   public void nestedGenericType_properlyEscaped() {
     refactoring