Strip trailing asterisks before */ in Javadoc comments.

Decorative closing delimiters such as `/** ... **/` previously had the trailing
asterisk retained as comment body content, resulting in `/** ... * */`.

Ported from google/google-java-format#1474 (commit 2957b192). In this fork
stripJavadocBeginAndEnd lives in JavadocLexer; the tests were written first
and failed with `* */` before the change.

Author: cushon

open-java-format/src/main/java/com/palantir/javaformat/java/javadoc/JavadocLexer.java

@@ -92,7 +92,11 @@ private static String stripJavadocBeginAndEnd(String input) {
          */
         checkArgument(input.startsWith("/**"), "Missing /**: %s", input);
         checkArgument(input.endsWith("*/") && input.length() > 4, "Missing */: %s", input);
-        return input.substring("/**".length(), input.length() - "*/".length());
+        int end = input.length() - "*/".length();
+        while (end > "/**".length() && input.charAt(end - 1) == '*') {
+            end--;
+        }
+        return input.substring("/**".length(), end);
     }
 
     private final CharStream input;

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

@@ -570,6 +570,35 @@ void significantAsterisks() {
         doFormatTest(input, expected);
     }
 
+    @Test
+    void trailingAsterisksBeforeClose() {
+        String[] input = {
+            "/** Version information for all the QuotaKeys that we have data for **/", //
+            "class Test {}",
+        };
+        String[] expected = {
+            "/** Version information for all the QuotaKeys that we have data for */", //
+            "class Test {}",
+        };
+        doFormatTest(input, expected);
+    }
+
+    @Test
+    void trailingAsterisksOnTheirOwnLine() {
+        String[] input = {
+            "/**", //
+            " * Summary line",
+            " * continues here.",
+            " ***/",
+            "class Test {}",
+        };
+        String[] expected = {
+            "/** Summary line continues here. */", //
+            "class Test {}",
+        };
+        doFormatTest(input, expected);
+    }
+
     @Test
     void links() {
         String[] input = {