fix unit test

Author: panchenko

servlet/src/main/java/io/grpc/servlet/ServletAdapter.java

@@ -22,6 +22,7 @@
 import static java.util.logging.Level.FINE;
 import static java.util.logging.Level.FINEST;
 
+import com.google.common.annotations.VisibleForTesting;
 import com.google.common.io.BaseEncoding;
 import io.grpc.Attributes;
 import io.grpc.ExperimentalApi;
@@ -160,7 +161,8 @@ public void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOEx
   /**
    * Deadlines are managed via Context, servlet async timeout is not supposed to happen.
    */
-  private static final long ASYNC_TIMEOUT_SAFETY_MARGIN = 5_000;
+  @VisibleForTesting
+  static final long ASYNC_TIMEOUT_SAFETY_MARGIN = 5_000;
 
   // This method must use Enumeration and its members, since that is the only way to read headers
   // from the servlet api.

servlet/src/test/java/io/grpc/servlet/ServletServerBuilderTest.java

@@ -80,7 +80,7 @@ public void scheduledExecutorService() throws Exception {
     ServletAdapter servletAdapter = serverBuilder.buildServletAdapter();
     servletAdapter.doPost(request, response);
 
-    verify(asyncContext).setTimeout(1);
+    verify(asyncContext).setTimeout(1 + ServletAdapter.ASYNC_TIMEOUT_SAFETY_MARGIN);
 
     // The following just verifies that scheduler is populated to the transport.
     // It doesn't matter what tasks (such as handshake timeout and request deadline) are actually