Add tests for obo authenticator for rerequest and type

Signed-off-by: Ryan Liang <jiallian@amazon.com>

src/test/java/org/opensearch/security/http/OnBehalfOfAuthenticatorTest.java

@@ -12,11 +12,7 @@
 package org.opensearch.security.http;
 
 import java.nio.charset.StandardCharsets;
-import java.util.Base64;
-import java.util.Collections;
-import java.util.Date;
-import java.util.HashMap;
-import java.util.Map;
+import java.util.*;
 
 import javax.crypto.SecretKey;
 
@@ -31,6 +27,7 @@
 import org.junit.Test;
 
 import org.opensearch.common.settings.Settings;
+import org.opensearch.security.filter.SecurityResponse;
 import org.opensearch.security.user.AuthCredentials;
 import org.opensearch.security.util.FakeRestRequest;
 
@@ -47,6 +44,20 @@ public class OnBehalfOfAuthenticatorTest {
     final static String signingKeyB64Encoded = BaseEncoding.base64().encode(signingKey.getBytes(StandardCharsets.UTF_8));
     final static SecretKey secretKey = Keys.hmacShaKeyFor(signingKeyB64Encoded.getBytes(StandardCharsets.UTF_8));
 
+    @Test
+    public void testReRequestAuthenticationReturnsEmptyOptional() {
+        OnBehalfOfAuthenticator authenticator = new OnBehalfOfAuthenticator(defaultSettings(), clusterName);
+        Optional<SecurityResponse> result = authenticator.reRequestAuthentication(null, null);
+        Assert.assertFalse(result.isPresent());
+    }
+
+    @Test
+    public void testGetTypeReturnsExpectedType() {
+        OnBehalfOfAuthenticator authenticator = new OnBehalfOfAuthenticator(defaultSettings(), clusterName);
+        String type = authenticator.getType();
+        Assert.assertEquals("onbehalfof_jwt", type);
+    }
+
     @Test
     public void testNoKey() {
         Exception exception = Assert.assertThrows(