[javadoc] Exclude \n from regex replacement in snippets

GitOrigin-RevId: 2e7993426c86cfb8b312878f895107a873c77e8f

java/java-impl/src/com/intellij/codeInsight/javadoc/SnippetMarkup.java

@@ -722,6 +722,11 @@ public class SnippetMarkup {
       Selector selector = replace.selector();
       String replacement = replace.replacement();
       if (selector instanceof Regex regex) {
+        boolean addLineBreak = false;
+        if (content.endsWith("\n")) {
+          content = content.substring(0, content.length() - 1);
+          addLineBreak = true;
+        }
         try {
           content = regex.pattern().matcher(StringUtil.newBombedCharSequence(content, 1000)).replaceAll(replacement);
         }
@@ -735,6 +740,9 @@ public class SnippetMarkup {
             replace.range(), JavaBundle.message("javadoc.snippet.error.malformed.replacement", "replace", replacement, e.getMessage()));
           visitor.visitError(replacementError);
         }
+        if (addLineBreak) {
+          content += "\n";
+        }
       }
       else if (selector instanceof Substring substring) {
         content = content.replace(substring.substring(), replacement);

java/java-tests/testSrc/com/intellij/java/codeInsight/javadoc/SnippetMarkupTest.java

@@ -376,6 +376,15 @@ public class SnippetMarkupTest {
     testVisitor("// @replace regex=\"(a*)*b\" replacement='z':\n" + str, null, true,
                 "Error: @replace: too complex regular expression '(a*)*b'\n" + str);
   }
+  
+  @Test
+  public void visitorRegexpDotAsterisk() {
+    testVisitor("""
+                  // @start region=main
+                  aaaa // @replace regex=".*" replacement="."
+                  // @end region=main
+                  """, null, true, "..\n");
+  }
 
   private static void testParsing(@NotNull String input, @NotNull String expected) {
     assertEquals(expected, SnippetMarkup.parse(input).toString());