question: public static Set < String > assertValidProtocols ( Set < String > expected , String [ ] protocols ) { assertNotNull ( protocols ) ; assertTrue ( protocols . length != 0 ) ; Set remainingProtocols = new HashSet < String > ( expected ) ; Set unknownProtocols = new HashSet < String > ( ) ; for ( String protocol : protocols ) { if ( ! remainingProtocols . remove ( protocol ) ) { unknownProtocols . add ( protocol ) ; } } assertEquals ( "Unknown protocols" , Collections . EMPTY_SET , unknownProtocols ) ; return remainingProtocols ; }
target:  Asserts that the protocols array is non-null and that it all of its contents are protocols known to this implementation. As a convenience, returns any unenabled protocols in a test for those that want to verify separately that all protocols were included.