### Question:
TokenFilter { public Set<CoreTokenField> getReturnFields() { return Collections.unmodifiableSet(returnFields); } TokenFilter(); QueryFilter<CoreTokenField> getQuery(); void setQuery(QueryFilter<CoreTokenField> query); Set<CoreTokenField> getReturnFields(); void addReturnAttribute(CoreTokenField field); String toString();  }### Answer:
@Test (expectedExceptions = UnsupportedOperationException.class) public void shouldPreventModificationToReturnAttributes() { filter.getReturnFields().clear(); }