Fix line break parsing after hard line break

Fixes #415.

Author: robinst

CHANGELOG.md

@@ -6,6 +6,11 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 This project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html),
 with the exception that 0.x versions can break between minor versions.
 
+## [Unreleased]
+### Fixed
+- Line(s) after a hard line break would sometimes also get an unwanted hard
+  line break, e.g. if they ended in emphasis or other non-text inlines (#415)
+
 ## [0.27.0] - 2025-10-12
 ### Added
 - Autolink extension: Now supports configuration of different link types that
@@ -510,6 +515,7 @@ API breaking changes (caused by changes in spec):
 Initial release of commonmark-java, a port of commonmark.js with extensions
 for autolinking URLs, GitHub flavored strikethrough and tables.
 
+[Unreleased]: https://github.com/commonmark/commonmark-java/compare/commonmark-parent-0.27.0...main
 [0.27.0]: https://github.com/commonmark/commonmark-java/compare/commonmark-parent-0.26.0...commonmark-parent-0.27.0
 [0.26.0]: https://github.com/commonmark/commonmark-java/compare/commonmark-parent-0.25.1...commonmark-parent-0.26.0
 [0.25.1]: https://github.com/commonmark/commonmark-java/compare/commonmark-parent-0.25.0...commonmark-parent-0.25.1

commonmark/src/main/java/org/commonmark/internal/InlineParserImpl.java

@@ -598,7 +598,9 @@ static String parseLinkLabel(Scanner scanner) {
     private Node parseLineBreak() {
         scanner.next();
 
-        if (trailingSpaces >= 2) {
+        var hard = trailingSpaces >= 2;
+        trailingSpaces = 0;
+        if (hard) {
             return new HardLineBreak();
         } else {
             return new SoftLineBreak();

commonmark/src/test/java/org/commonmark/test/CoreRenderingTestCase.java

@@ -11,6 +11,7 @@ public class CoreRenderingTestCase extends RenderingTestCase {
 
     @Override
     protected String render(String source) {
-        return RENDERER.render(PARSER.parse(source));
+        var node = PARSER.parse(source);
+        return RENDERER.render(node);
     }
 }

commonmark/src/test/java/org/commonmark/test/SpecialInputTest.java

@@ -210,4 +210,19 @@ public void htmlBlockInterruptingList() {
                 "</ul>\n" +
                 "</script>\n");
     }
+
+    @Test
+    public void emphasisAfterHardLineBreak() {
+        assertRendering("Hello  \n" +
+                "**Bar**\n" +
+                "Foo\n", "<p>Hello<br />\n" +
+                "<strong>Bar</strong>\n" +
+                "Foo</p>\n");
+
+        assertRendering("Hello  \n" +
+                "**Bar**  \n" +
+                "Foo\n", "<p>Hello<br />\n" +
+                "<strong>Bar</strong><br />\n" +
+                "Foo</p>\n");
+    }
 }