Null check while creating GraphError when body is empty.

Author: Nakul Sabharwal

src/main/java/com/microsoft/graph/http/GraphServiceException.java

@@ -311,7 +311,10 @@ public static <T> GraphServiceException createFromConnection(final IHttpRequest
         }
 
         final String responseMessage = connection.getResponseMessage();
-        final String rawOutput = DefaultHttpProvider.streamToString(connection.getInputStream());
+        String rawOutput = "{}";
+        if(connection.getInputStream() != null) {
+        	rawOutput = DefaultHttpProvider.streamToString(connection.getInputStream());
+        }
         GraphErrorResponse error;
         try {
             error = serializer.deserializeObject(rawOutput, GraphErrorResponse.class, connection.getResponseHeaders());

src/test/java/com/microsoft/graph/http/GraphServiceExceptionTests.java

@@ -4,7 +4,9 @@
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
+import java.io.ByteArrayInputStream;
 import java.io.IOException;
+import java.io.InputStream;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.Map;
@@ -80,5 +82,47 @@ public Map<String, String> getHeaders() {
         assertTrue(message.indexOf("Error code: Unable to parse error response message") == 0);
         assertTrue(message.indexOf("http://localhost") > 0);
     }
+	
+	@Test
+	public void testNullConnection() {
+		DefaultLogger logger = new DefaultLogger();
+        GraphServiceException exception = null;
+        Boolean success = false;
+        Boolean failure = false;
+        final ITestConnectionData data = new ITestConnectionData() {
+            @Override
+            public int getRequestCode() {
+                return 401;
+            }
+
+            @Override
+            public String getJsonResponse() {
+                return "{}";
+            }
+
+            @Override
+            public Map<String, String> getHeaders() {
+                return new HashMap<>();
+            }
+        };
+        try{
+            exception = GraphServiceException.createFromConnection(new MockHttpRequest(),null,null,new MockConnection(data) {
+            	@Override
+            	public InputStream getInputStream() throws IOException {
+                    return null;
+                }
+            },logger);
+            success = true;
+        }catch (IOException ex){
+            failure = true;
+        }
+
+        assertTrue(success);
+        assertFalse(failure);
+
+        String message = exception.getMessage();
+        assertTrue(message.indexOf("Error code: Unable to parse error response message") == 0);
+        assertTrue(message.indexOf("http://localhost") > 0);
+    }
 
 }