Wrap error fixes and doNotCompleteOnReturn (#7)

* Wrap fixes and doNotCompleteOnReturn

* Comment fixed

Author: mfateev

src/main/java/com/uber/cadence/samples/fileprocessing/StoreActivitiesImpl.java

@@ -51,7 +51,7 @@ public TaskListFileNamePair download(URL url) {
             System.out.println("download activity: downloaded from " + url + " to " + destination.getAbsolutePath());
             return new TaskListFileNamePair(hostSpecificTaskList, destination.getAbsolutePath());
         } catch (IOException e) {
-            throw Workflow.throwWrapped(e);
+            throw Workflow.wrap(e);
         }
     }
 
@@ -63,7 +63,7 @@ public String process(String sourceFile) {
             System.out.println("process activity: processed file: " + processedName);
             return processedName;
         } catch (IOException e) {
-            throw Activity.throwWrapped(e);
+            throw Activity.wrap(e);
         }
     }
 

src/main/java/com/uber/cadence/samples/hello/HelloAsyncActivityCompletion.java

@@ -18,7 +18,6 @@
 
 import com.uber.cadence.activity.Activity;
 import com.uber.cadence.activity.ActivityMethod;
-import com.uber.cadence.activity.DoNotCompleteOnReturn;
 import com.uber.cadence.client.ActivityCompletionClient;
 import com.uber.cadence.client.WorkflowClient;
 import com.uber.cadence.worker.Worker;
@@ -76,17 +75,17 @@ private static class GreetingActivitiesImpl implements GreetingActivities {
 
         /**
          * Demonstrates how implement an activity asynchronously.
-         * When @DoNotCompleteOnReturn is present activity implementation function returning doesn't complete
-         * the activity.
+         * When {@link Activity#doNotCompleteOnReturn()} is called the activity implementation function returning
+         * doesn't complete the activity.
          */
-        @DoNotCompleteOnReturn
         @Override
         public String composeGreeting(String greeting, String name) {
             // TaskToken is a correlation token used to match activity task with completion
             byte[] taskToken = Activity.getTaskToken();
             // In real life this request can be executed anywhere. By external service for example.
             ForkJoinPool.commonPool().execute(() -> composeGreetingAsync(taskToken, greeting, name));
-            // When @DoNotCompleteOnReturn is specified the return value is ignored.
+            Activity.doNotCompleteOnReturn();
+            // When doNotCompleteOnReturn() is invoked the return value is ignored.
             return "ignored";
         }
 

src/main/java/com/uber/cadence/samples/hello/HelloException.java

@@ -88,7 +88,7 @@
  * activity, child and workflow interfaces is not going to help. It is because at all levels it is never received directly, but
  * in wrapped form. Propagating it without wrapping would not allow adding additional context information
  * like activity, child workflow and parent workflow  types and IDs. The Cadence library solution is to provide special
- * wrapper method {@link Workflow#throwWrapped(Throwable)} which wraps a checked exception in a special runtime exception.
+ * wrapper method {@link Workflow#wrap(Exception)} which wraps a checked exception in a special runtime exception.
  * It is special because framework strips it when chaining exception across logical process boundaries. In this example
  * IOException is directly attached to ActivityFailureException besides being wrapped when rethrown.
  * </p>
@@ -147,7 +147,9 @@ public String composeGreeting(String greeting, String name) {
             try {
                 throw new IOException(greeting + " " + name + "!");
             } catch (IOException e) {
-                throw Workflow.throwWrapped(e);
+                // Wrap it as checked exceptions in activity and workflow interface methods are prohibited.
+                // It will be unwrapped and attached as a cause to the ActivityFailureException.
+                throw Workflow.wrap(e);
             }
         }
     }