Remove the need for an OAuth API mode

src/main/java/com/stripe/net/ApiMode.java

@@ -1,6 +1,5 @@
 package com.stripe.net;
 
 public enum ApiMode {
-  V1,
-  OAuth
+  V1
 }

src/main/java/com/stripe/net/LiveStripeResponseGetter.java

@@ -1,6 +1,7 @@
 package com.stripe.net;
 
 import com.google.gson.JsonObject;
+import com.google.gson.JsonPrimitive;
 import com.google.gson.JsonSyntaxException;
 import com.stripe.Stripe;
 import com.stripe.exception.*;
@@ -102,7 +103,7 @@ public <T extends StripeObjectInterface> T request(ApiRequest apiRequest, Type t
     String requestId = response.requestId();
 
     if (responseCode < 200 || responseCode >= 300) {
-      handleError(response, apiRequest.getApiMode());
+      handleError(response);
     }
 
     T resource = null;
@@ -151,7 +152,7 @@ public InputStream requestStream(ApiRequest apiRequest) throws StripeException {
                 Stripe.getApiBase(), e.getMessage()),
             e);
       }
-      handleError(response, apiRequest.getApiMode());
+      handleError(response);
     }
 
     return responseStream.body();
@@ -202,11 +203,21 @@ private static void raiseMalformedJsonError(
         e);
   }
 
-  private void handleError(StripeResponse response, ApiMode apiMode) throws StripeException {
-    if (apiMode == ApiMode.V1) {
+  private void handleError(StripeResponse response) throws StripeException {
+    JsonObject responseBody = ApiResource.GSON.fromJson(response.body(), JsonObject.class);
+
+    /*
+     OAuth errors are JSON objects where `error` is a string. In
+     contrast, in API errors, `error` is a hash with sub-keys. We use
+     this property to distinguish between OAuth and API errors.
+    */
+    if (responseBody.has("error") && responseBody.get("error").isJsonPrimitive()) {
+      JsonPrimitive error = responseBody.getAsJsonPrimitive("error");
+      if (error.isString()) {
+        handleOAuthError(response);
+      }
+    } else {
       handleApiError(response);
-    } else if (apiMode == ApiMode.OAuth) {
-      handleOAuthError(response);
     }
   }
 

src/main/java/com/stripe/net/OAuth.java

@@ -53,7 +53,7 @@ public static TokenResponse token(Map<String, Object> params, RequestOptions opt
             "/oauth/token",
             params,
             options,
-            ApiMode.OAuth);
+            ApiMode.V1);
     return OAuth.globalResponseGetter.request(request, TokenResponse.class);
   }
 
@@ -77,7 +77,7 @@ public static DeauthorizedAccount deauthorize(Map<String, Object> params, Reques
             "/oauth/deauthorize",
             paramsCopy,
             options,
-            ApiMode.OAuth);
+            ApiMode.V1);
     return OAuth.globalResponseGetter.request(request, DeauthorizedAccount.class);
   }
 

src/test/java/com/stripe/BaseStripeTest.java

@@ -9,7 +9,6 @@
 import com.stripe.exception.StripeException;
 import com.stripe.model.StripeObjectInterface;
 import com.stripe.net.*;
-import com.stripe.net.ApiMode;
 import java.io.BufferedReader;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
@@ -347,12 +346,7 @@ public static <T extends StripeObjectInterface> void stubOAuthRequest(
       Class<T> clazz, String response) throws StripeException {
     Mockito.doReturn(ApiResource.GSON.fromJson(response, clazz))
         .when(networkSpy)
-        .request(
-            Mockito.argThat(
-                (req) -> {
-                  return req.getApiMode() == ApiMode.OAuth;
-                }),
-            Mockito.<Type>any());
+        .request(Mockito.any(ApiRequest.class), Mockito.<Type>any());
   }
 
   /**