### Question:
DelegatingContentHandlerImpl implements FileContentReferenceHandler { @Override public boolean isContentReferenceExists(ContentReference contentReference) { ContentReferenceHandler delegate = getDelegate(contentReference); return delegate.isContentReferenceExists(contentReference); }  void setDelegates(List<ContentReferenceHandler> delegates); @Override boolean isContentReferenceSupported(ContentReference contentReference); @Override boolean isContentReferenceExists(ContentReference contentReference); @Override ContentReference createContentReference(String fileName, String mediaType); @Override InputStream getInputStream(ContentReference contentReference, boolean waitForAvailability); @Override long putInputStream(InputStream sourceInputStream, ContentReference targetContentReference); @Override long putFile(File sourceFile, ContentReference targetContentReference); @Override void delete(ContentReference contentReference); @Override boolean isAvailable(); @Override File getFile(ContentReference contentReference, boolean waitForTransfer);  }### Answer:
@Test public void testIsContentReferenceExists() { assertTrue(delegatingHandler.isContentReferenceExists(contentReferenceFile1a)); assertTrue(delegatingHandler.isContentReferenceExists(contentReferenceFile1b)); thrown.expect(UnsupportedOperationException.class); delegatingHandler.isContentReferenceExists(contentReferenceFile1c); }