Filter filter = searchRequest.getFilter();
assertTrue( filter instanceof SubstringFilter );
SubstringFilter substringFilter = ( SubstringFilter ) filter;
assertEquals( "jack", substringFilter.getInitialSubstrings() );
List<String> initials = substringFilter.getAnySubstrings();
assertEquals( 1, initials.size() );
assertEquals( "kate", initials.get( 0 ).toString() );
}