title: EasyMock incompatible return value type for return type Collection
body: <p>I am getting the following exception for a method where the return type of the method is collection...</p>
  
  <pre><code>java.lang.IllegalStateException: incompatible return value type
  at org.easymock.internal.MocksControl.andReturn(MocksControl.java:218)
  
  expect(training.getTrainingMaterials()).andReturn(new HashSet());
  </code></pre>
  
  <p>where the <code>training.getTrainingMaterials()</code> --> return type is Collection..</p>
  
  <p>Can you please help me what needs to be done?</p>
  
  <p>Thanks.</p>