diff --git a/src/intTest/java/com/box/sdk/BoxAPIConnectionIT.java b/src/intTest/java/com/box/sdk/BoxAPIConnectionIT.java
index 1603c0f63..f52631887 100644
--- a/src/intTest/java/com/box/sdk/BoxAPIConnectionIT.java
+++ b/src/intTest/java/com/box/sdk/BoxAPIConnectionIT.java
@@ -33,78 +33,49 @@ public void requestIsSentNormallyWhenInterceptorReturnsNullResponse() throws Mal
     }
 
     @Test
-    @Ignore("Need to configure access and refresh token")
     public void refreshSucceeds() {
-        final String originalAccessToken = TestConfig.getAccessToken();
-        final String originalRefreshToken = TestConfig.getRefreshToken();
-        BoxAPIConnection api = new BoxAPIConnection(TestConfig.getClientID(), TestConfig.getClientSecret(),
-            originalAccessToken, originalRefreshToken);
+        BoxAPIConnection api = jwtApiForServiceAccount();
+        String originalAccessToken = api.getAccessToken();
 
         api.refresh();
 
         String actualAccessToken = api.getAccessToken();
-        String actualRefreshToken = api.getRefreshToken();
 
-        assertThat(originalRefreshToken, not(equalTo(actualRefreshToken)));
         assertThat(originalAccessToken, not(equalTo(actualAccessToken)));
-
-        TestConfig.setAccessToken(actualAccessToken);
-        TestConfig.setRefreshToken(actualRefreshToken);
     }
 
     @Test
-    @Ignore("Need to configure access and refresh token")
     public void refreshesWhenGetAccessTokenIsCalledAndTokenHasExpired() {
-        final String originalAccessToken = TestConfig.getAccessToken();
-        final String originalRefreshToken = TestConfig.getRefreshToken();
-        BoxAPIConnection api = new BoxAPIConnection(TestConfig.getClientID(), TestConfig.getClientSecret(),
-            originalAccessToken, originalRefreshToken);
+        BoxAPIConnection api = jwtApiForServiceAccount();
+        String originalAccessToken = api.getAccessToken();
         api.setExpires(-1);
 
         String actualAccessToken = api.getAccessToken();
-        String actualRefreshToken = api.getRefreshToken();
 
-        assertThat(originalRefreshToken, not(equalTo(actualRefreshToken)));
         assertThat(originalAccessToken, not(equalTo(actualAccessToken)));
-
-        TestConfig.setAccessToken(actualAccessToken);
-        TestConfig.setRefreshToken(actualRefreshToken);
     }
 
     @Test
-    @Ignore("Need to configure access and refresh token")
     public void doesNotRefreshWhenGetAccessTokenIsCalledAndTokenHasNotExpired() {
-        final String originalAccessToken = TestConfig.getAccessToken();
-        final String originalRefreshToken = TestConfig.getRefreshToken();
-        BoxAPIConnection api = new BoxAPIConnection(TestConfig.getClientID(), TestConfig.getClientSecret(),
-            originalAccessToken, originalRefreshToken);
+        BoxAPIConnection api = jwtApiForServiceAccount();
+        String originalAccessToken = api.getAccessToken();
         api.setExpires(Long.MAX_VALUE);
 
         String actualAccessToken = api.getAccessToken();
-        String actualRefreshToken = api.getRefreshToken();
 
-        assertThat(originalRefreshToken, equalTo(actualRefreshToken));
         assertThat(originalAccessToken, equalTo(actualAccessToken));
-
-        TestConfig.setAccessToken(actualAccessToken);
-        TestConfig.setRefreshToken(actualRefreshToken);
     }
 
     @Test
-    @Ignore("Need to configure access and refresh token")
     public void successfullySavesAndRestoresConnection() {
-        final String originalAccessToken = TestConfig.getAccessToken();
-        final String originalRefreshToken = TestConfig.getRefreshToken();
-        BoxAPIConnection api = new BoxAPIConnection(TestConfig.getClientID(), TestConfig.getClientSecret(),
-            originalAccessToken, originalRefreshToken);
+        BoxAPIConnection api = jwtApiForServiceAccount();
         String state = api.save();
+        BoxConfig boxConfig = jwtBoxConfig();
 
-        BoxAPIConnection restoredAPI = BoxAPIConnection.restore(TestConfig.getClientID(), TestConfig.getClientSecret(),
-            state);
-        BoxFolder.getRootFolder(restoredAPI).getInfo();
-
-        TestConfig.setAccessToken(restoredAPI.getAccessToken());
-        TestConfig.setRefreshToken(restoredAPI.getRefreshToken());
+        BoxAPIConnection restoredAPI = BoxAPIConnection.restore(
+            boxConfig.getClientId(), boxConfig.getClientSecret(), state
+        );
+        assertThat(BoxFolder.getRootFolder(restoredAPI).getInfo().getID(), is("0"));
     }
 
     @Test
diff --git a/src/main/java/com/box/sdk/BoxAPIConnection.java b/src/main/java/com/box/sdk/BoxAPIConnection.java
index 6e7e86573..0c42b1d41 100644
--- a/src/main/java/com/box/sdk/BoxAPIConnection.java
+++ b/src/main/java/com/box/sdk/BoxAPIConnection.java
@@ -830,7 +830,9 @@ public void refresh() {
     public void restore(String state) {
         JsonObject json = Json.parse(state).asObject();
         String accessToken = json.get("accessToken").asString();
-        String refreshToken = json.get("refreshToken").asString();
+        String refreshToken = Optional.ofNullable(json.get("refreshToken"))
+            .map(v -> v.isNull() ? null : v.asString())
+            .orElse(null);
         long lastRefresh = json.get("lastRefresh").asLong();
         long expires = json.get("expires").asLong();
         String userAgent = json.get("userAgent").asString();
diff --git a/src/test/java/com/box/sdk/BoxAPIRequestTest.java b/src/test/java/com/box/sdk/BoxAPIRequestTest.java
index 9e47f6b15..ba41a4858 100644
--- a/src/test/java/com/box/sdk/BoxAPIRequestTest.java
+++ b/src/test/java/com/box/sdk/BoxAPIRequestTest.java
@@ -2,6 +2,7 @@
 
 import static com.box.sdk.http.ContentType.APPLICATION_JSON;
 import static com.github.tomakehurst.wiremock.client.WireMock.aResponse;
+import static com.github.tomakehurst.wiremock.client.WireMock.equalTo;
 import static com.github.tomakehurst.wiremock.client.WireMock.get;
 import static com.github.tomakehurst.wiremock.client.WireMock.getRequestedFor;
 import static com.github.tomakehurst.wiremock.client.WireMock.matching;
@@ -234,6 +235,23 @@ public void willNotRetry400ErrorWithJsonResponse() {
         }
     }
 
+    @Test
+    public void interceptorCanModifyRequest() {
+        String headerName = "XX-My-Custom-Header";
+        String headerValue = "some value";
+        stubFor(get(urlEqualTo("/")).withHeader(headerName, equalTo(headerValue))
+            .willReturn(aResponse().withStatus(200).withBody("{\"foo\":\"bar\"}")));
+
+        BoxAPIConnection api = new BoxAPIConnection("");
+        api.setRequestInterceptor(request -> {
+            request.addHeader(headerName, headerValue);
+            return null;
+        });
+
+        new BoxAPIRequest(api, boxMockUrl(), "GET").send();
+        verify(1, getRequestedFor(urlEqualTo("/")));
+    }
+
     private byte[] gzipped(String str) {
         try {
             ByteArrayOutputStream obj = new ByteArrayOutputStream();