Leave a comment that opens with /*** out of javadoc formatting

open-java-format/src/main/java/com/palantir/javaformat/java/JavaInput.java

@@ -154,7 +154,9 @@ public boolean isSlashStarComment() {
 
         @Override
         public boolean isJavadocComment() {
-            return text.startsWith("/**") && text.length() > 4;
+            // comments like `/***` are also javadoc, but their formatting probably won't be improved
+            // by the javadoc formatter
+            return text.startsWith("/**") && text.charAt("/**".length()) != '*' && text.length() > 4;
         }
 
         @Override

open-java-format/src/test/java/com/palantir/javaformat/java/JavadocFormattingTest.java

@@ -55,11 +55,28 @@ public void empty() {
             "class Test {}",
         };
         String[] expected = {
-            "/** */", "class Test {}",
+            "/***/", "class Test {}",
         };
         doFormatTest(input, expected);
     }
 
+    @Test
+    public void bannerCommentIsNotJavadoc() {
+        // A comment that opens with three or more asterisks is left to the plain comment handling: reflowing it as
+        // javadoc would push the asterisks onto a line of their own and turn its paragraphs into <p> tags.
+        String[] input = {
+            "/****************************************",
+            " * Copyright",
+            " *",
+            " * Some",
+            " *",
+            " * Company",
+            " ****************************************/",
+            "class Test {}",
+        };
+        doFormatTest(input, input);
+    }
+
     @Test
     public void emptyMultipleLines() {
         String[] input = {