Token re fetch logic implementation

examples/BearerTokenAuthentication.md

@@ -0,0 +1,15 @@
+    class BearerTokenAuthenticationExamples {
+        public static void main {
+            //Getting access token
+            Token token  = Token.creator(GRANT_TYPE, CLIENT_ID).setClientSecret(CLIENT_SECRET).create();
+
+            TwilioBearerTokenAuth.init(token.getAccessToken());
+            fetchAccountDetails();
+        }
+
+        private static void fetchAccountDetails() {
+           ResourceSet<Account> accountSet = Account.reader(ORGANISATION_ID).read();
+           String accountSid = accountSet.iterator().next().getAccountSid();
+           System.out.println(accountSid);
+        }
+    }

src/main/java/com/twilio/TwilioBearerTokenAuth.java

@@ -25,15 +25,12 @@ public class TwilioBearerTokenAuth {
     private TwilioBearerTokenAuth() {
     }
 
-    public static synchronized void init(final String accessToken, final TokenManager tokenManager) {
-        if (accessToken == null || accessToken.isEmpty()) {
-            throw new AuthenticationException("Access Token can not be null or Empty");
+    public static synchronized void init(final TokenManager tokenManager) {
+        if (tokenManager == null) {
+            throw new AuthenticationException("Token Manager cannot be null");
         }
-        if (!accessToken.equals(TwilioBearerTokenAuth.accessToken)) {
-            TwilioBearerTokenAuth.invalidate();
-        }
-        TwilioBearerTokenAuth.accessToken = accessToken;
         TwilioBearerTokenAuth.tokenManager = tokenManager;
+        TwilioBearerTokenAuth.accessToken = tokenManager.fetchAccessToken();
     }
 
     public static BearerTokenTwilioRestClient getRestClient() {

src/main/java/com/twilio/base/noauth/Creator.java

@@ -2,7 +2,7 @@
 
 import com.twilio.Twilio;
 import com.twilio.TwilioNoAuth;
-import com.twilio.base.Resource;
+import com.twilio.base.noauth.Resource;
 import com.twilio.http.noauth.NoAuthTwilioRestClient;
 
 import java.util.concurrent.CompletableFuture;

src/main/java/com/twilio/base/noauth/Fetcher.java

@@ -3,7 +3,7 @@
 import com.twilio.Twilio;
 
 import com.twilio.TwilioNoAuth;
-import com.twilio.base.Resource;
+import com.twilio.base.noauth.Resource;
 import com.twilio.http.noauth.NoAuthTwilioRestClient;
 
 import java.util.concurrent.CompletableFuture;

src/main/java/com/twilio/base/noauth/Resource.java

@@ -0,0 +1,9 @@
+package com.twilio.base.noauth;
+
+import java.io.Serializable;
+
+public abstract class Resource implements Serializable {
+
+    private static final long serialVersionUID = -5898012691404059592L;
+
+}

src/main/java/com/twilio/http/bearertoken/TokenManager.java

@@ -2,5 +2,5 @@
 
 public interface TokenManager {
     public String refreshAccessToken(String refreshToken);
-    public synchronized String fetchAccessToken();
+    public String fetchAccessToken();
 }

src/main/java/com/twilio/http/bearertoken/TokenManagerImpl.java

@@ -18,7 +18,7 @@ public String refreshAccessToken(String refreshToken){
         return token.getAccessToken();
     }
 
-    public synchronized String fetchAccessToken(){
+    public String fetchAccessToken(){
         Token token = Token.creator(grantType, clientId).setClientSecret(clientSecret).create();
         return token.getAccessToken();
     }