Fixed IDEA-143120 Javadoc HTML proper formatting

merged HTML lines with "wrapped at right margin" option

java/java-impl/src/com/intellij/psi/impl/source/codeStyle/javadoc/JDParser.java

@@ -422,14 +422,8 @@ public class JDParser {
         result.add(Pair.create(s1, marks[i]));
       }
       else {
-        if (s1.isEmpty() || s1.equals(SELF_CLOSED_P_TAG)) {
-          if (sb.length() != 0) {
-            result.add(new Pair<>(sb.toString(), false));
-            sb.setLength(0);
-          }
-          result.add(Pair.create(s1, marks[i]));
-        }
-        else if (mySettings.JD_PRESERVE_LINE_FEEDS) {
+        if (s1.isEmpty() || s1.equals(SELF_CLOSED_P_TAG) || isKeepLineFeedsIn(s1)) {
+          endParagraph(result, sb);
           result.add(Pair.create(s1, marks[i]));
         }
         else {
@@ -444,6 +438,24 @@ public class JDParser {
     return result;
   }
 
+  private boolean isKeepLineFeedsIn(@NotNull String line) {
+    return mySettings.JD_PRESERVE_LINE_FEEDS || startsWithTag(line);
+  }
+
+  private static boolean startsWithTag(@NotNull String line) {
+    if (line.trim().startsWith("<")) {
+      return line.matches("\\s*</?\\w+>.*");
+    }
+    return false;
+  }
+
+  private static void endParagraph(@NotNull List<Pair<String, Boolean>> result, @NotNull StringBuilder sb) {
+    if (sb.length() > 0) {
+      result.add(new Pair<>(sb.toString(), false));
+      sb.setLength(0);
+    }
+  }
+
   private interface TagParser {
     boolean parse(String tag, String line, JDComment c);
   }

java/java-tests/testSrc/com/intellij/java/psi/formatter/java/JavadocFormatterTest.kt

@@ -1023,4 +1023,63 @@ module M {
 module M {
 }""")
   }
+
+  fun testRichHtml() {
+    getSettings().WRAP_COMMENTS = true
+    getSettings().RIGHT_MARGIN = 50
+    getJavaSettings().JD_ADD_BLANK_AFTER_DESCRIPTION = false
+    doTextTest(
+      """public class Test {
+    /**
+     * <h1>A description containing HTML tags</h1>
+     * <p>
+     *     There might be lists in descriptions like this one:
+     *     <ul>
+     *         <li>Item one</li>
+     *         <li>Item two</li>
+     *         <li>Item three</li>
+     *     </ul>
+     *     which should be left as is, without any tags merged.
+     * </p>
+     * @param a Parameter descriptions can also be long but tag
+     *          content should be left intact:
+     *          <ol>
+     *          <li>Another item one</li>
+     *          <li>Item two</li>
+     *          </ol>
+     */
+    void test(int a) {
+    }
+}
+""",
+
+      """public class Test {
+    /**
+     * <h1>A description containing HTML
+     * tags</h1>
+     * <p>
+     * There might be lists in descriptions like
+     * this one:
+     * <ul>
+     * <li>Item one</li>
+     * <li>Item two</li>
+     * <li>Item three</li>
+     * </ul>
+     * which should be left as is, without any
+     * tags merged.
+     * </p>
+     * @param a Parameter descriptions can also be
+     *          long but tag content should be
+     *          left intact:
+     *          <ol>
+     *          <li>Another item one</li>
+     *          <li>Item two</li>
+     *          </ol>
+     */
+    void test(int a) {
+    }
+}
+"""
+    )
+  }
 }