Add enum for HTTP status codes and helper methods

Author: Avery-Dunn

msal4j-sdk/src/main/java/com/microsoft/aad/msal4j/DefaultRetryPolicy.java

@@ -12,8 +12,7 @@ class DefaultRetryPolicy implements IRetryPolicy {
 
     @Override
     public boolean isRetryable(IHttpResponse httpResponse) {
-        return httpResponse.statusCode() >= 500 &&
-                httpResponse.statusCode() < 600 &&
+        return HttpStatus.isServerError(httpResponse.statusCode()) &&
                 HttpHelper.getRetryAfterHeader(httpResponse) == null;
     }
 

msal4j-sdk/src/main/java/com/microsoft/aad/msal4j/HttpStatus.java

@@ -0,0 +1,38 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+package com.microsoft.aad.msal4j;
+
+enum HttpStatus {
+    OK(200, "OK"),
+    FOUND(302, "Found"),
+    BAD_REQUEST(400, "Bad Request"),
+    NOT_FOUND(404, "Not Found"),
+    REQUEST_TIMEOUT(408, "Request Timeout"),
+    GONE(410, "Gone"),
+    TOO_MANY_REQUESTS(429, "Too Many Requests"),
+    INTERNAL_SERVER_ERROR(500, "Internal Server Error"),
+    SERVICE_UNAVAILABLE(503, "Service Unavailable"),
+    GATEWAY_TIMEOUT(504, "Gateway Timeout");
+
+    private final int code;
+    private final String description;
+
+    HttpStatus(int code, String description) {
+        this.code = code;
+        this.description = description;
+    }
+
+    int getCode() {
+        return code;
+    }
+
+    String getDescription() {
+        return description;
+    }
+
+    //All 5xx errors
+    static boolean isServerError(int code) {
+        return code >= 500 && code < 600;
+    }
+}

msal4j-sdk/src/main/java/com/microsoft/aad/msal4j/IMDSRetryPolicy.java

@@ -18,11 +18,11 @@ public boolean isRetryable(IHttpResponse httpResponse) {
         currentRetryCount++;
         lastStatusCode = httpResponse.statusCode();
 
-        return (lastStatusCode >= 500 && lastStatusCode < 600) ||
-                lastStatusCode == 404 || // Not Found
-                lastStatusCode == 408 || // Request Timeout
-                lastStatusCode == 410 || // Gone
-                lastStatusCode == 429;   // Too Many Requests
+        return HttpStatus.isServerError(lastStatusCode) ||
+                lastStatusCode == HttpStatus.NOT_FOUND.getCode() ||
+                lastStatusCode == HttpStatus.REQUEST_TIMEOUT.getCode() ||
+                lastStatusCode == HttpStatus.GONE.getCode() ||
+                lastStatusCode == HttpStatus.TOO_MANY_REQUESTS.getCode();
     }
 
     @Override

msal4j-sdk/src/main/java/com/microsoft/aad/msal4j/ManagedIdentityRetryPolicy.java

@@ -14,12 +14,12 @@ class ManagedIdentityRetryPolicy implements IRetryPolicy {
     public boolean isRetryable(IHttpResponse httpResponse) {
         int statusCode = httpResponse.statusCode();
 
-        return statusCode == 404 || // Not Found
-                statusCode == 408 || // Request Timeout
-                statusCode == 429 || // Too Many Requests
-                statusCode == 500 || // Internal Server Error
-                statusCode == 503 || // Service Unavailable
-                statusCode == 504;   // Gateway Timeout
+        return statusCode == HttpStatus.NOT_FOUND.getCode() ||
+                statusCode == HttpStatus.REQUEST_TIMEOUT.getCode() ||
+                statusCode == HttpStatus.TOO_MANY_REQUESTS.getCode() ||
+                statusCode == HttpStatus.INTERNAL_SERVER_ERROR.getCode() ||
+                statusCode == HttpStatus.SERVICE_UNAVAILABLE.getCode() ||
+                statusCode == HttpStatus.GATEWAY_TIMEOUT.getCode();
     }
 
     @Override