### Question:
DelegatingContentHandlerImpl implements FileContentReferenceHandler { @Override public boolean isAvailable() { for (ContentReferenceHandler delegate : delegates) { if (!delegate.isAvailable()) { return false; } } return true; }  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 testIsAvailable() { assertTrue(delegatingHandler.isAvailable()); ((FileContentReferenceHandlerImpl) handlerA).setFileProvider(null); assertFalse(delegatingHandler.isAvailable()); }