Added ActivityInterface hierarchy test

Author: mfateev

src/main/java/com/uber/cadence/internal/sync/POJOActivityTaskHandler.java

@@ -17,6 +17,7 @@
 
 package com.uber.cadence.internal.sync;
 
+import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Joiner;
 import com.google.common.base.Objects;
 import com.uber.cadence.PollForActivityTaskResponse;
@@ -158,6 +159,11 @@ public boolean isAnyTypeSupported() {
     return !activities.isEmpty();
   }
 
+  @VisibleForTesting
+  public Set<String> getRegisteredActivityTypes() {
+    return activities.keySet();
+  }
+
   void setActivitiesImplementation(Object[] activitiesImplementation) {
     activities.clear();
     for (Object activity : activitiesImplementation) {

src/test/java/com/uber/cadence/worker/ActivityInterfaceTest.java renamed to src/test/java/com/uber/cadence/internal/sync/ActivityInterfaceTest.java

@@ -15,7 +15,7 @@
  *  permissions and limitations under the License.
  */
 
-package com.uber.cadence.worker;
+package com.uber.cadence.internal.sync;
 
 import com.google.common.base.Objects;
 import com.uber.cadence.activity.ActivityInterface;