HOTFIX: Fix lgtm.com alerts (dead code and out-of-bounds error) (#4388)

This fixes two alerts flagged on lgtm.com for Apache Kafka.

This dead code alert where InvalidTypeIdException indirectly extends JsonMappingException. The flagged condition with the type test appears after the type test for the latter and thus makes its body dead. I opted to change the order of the tests. Please let me know if this is the intended behavior.

The second commit addresses this out-of-bounds alert.

More alerts can be found here. Note that my colleague Aditya Sharad addressed some of those in the now outdated #2939.

Reviewers: Matthias J. Sax <matthias@confluent.io>, Rajini Sivaram <rajinisivaram@googlemail.com>

clients/src/main/java/org/apache/kafka/common/security/kerberos/KerberosRule.java

@@ -107,8 +107,8 @@ class KerberosRule {
     }
 
     /**
-     * Replace the numbered parameters of the form $n where n is from 1 to
-     * the length of params. Normal text is copied directly and $n is replaced
+     * Replace the numbered parameters of the form $n where n is from 0 to
+     * the length of params - 1. Normal text is copied directly and $n is replaced
      * by the corresponding parameter.
      * @param format the string to replace parameters again
      * @param params the list of parameters
@@ -126,7 +126,7 @@ class KerberosRule {
             if (paramNum != null) {
                 try {
                     int num = Integer.parseInt(paramNum);
-                    if (num < 0 || num > params.length) {
+                    if (num < 0 || num >= params.length) {
                         throw new BadFormatString("index " + num + " from " + format +
                                 " is outside of the valid range 0 to " +
                                 (params.length - 1));

clients/src/test/java/org/apache/kafka/common/security/kerberos/KerberosRuleTest.java

@@ -0,0 +1,49 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.kafka.common.security.kerberos;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+
+import org.junit.Test;
+
+public class KerberosRuleTest {
+
+    @Test
+    public void testReplaceParameters() throws BadFormatString {
+        // positive test cases
+        assertEquals(KerberosRule.replaceParameters("", new String[0]), "");
+        assertEquals(KerberosRule.replaceParameters("hello", new String[0]), "hello");
+        assertEquals(KerberosRule.replaceParameters("", new String[]{"too", "many", "parameters", "are", "ok"}), "");
+        assertEquals(KerberosRule.replaceParameters("hello", new String[]{"too", "many", "parameters", "are", "ok"}), "hello");
+        assertEquals(KerberosRule.replaceParameters("hello $0", new String[]{"too", "many", "parameters", "are", "ok"}), "hello too");
+        assertEquals(KerberosRule.replaceParameters("hello $0", new String[]{"no recursion $1"}), "hello no recursion $1");
+
+        // negative test cases
+        try {
+            KerberosRule.replaceParameters("$0", new String[]{});
+            fail("An out-of-bounds parameter number should trigger an exception!");
+        } catch (BadFormatString bfs) {
+        }
+        try {
+            KerberosRule.replaceParameters("hello $a", new String[]{"does not matter"});
+            fail("A malformed parameter name should trigger an exception!");
+        } catch (BadFormatString bfs) {
+        }
+    }
+
+}