question: public static URI determineFinalEndpoint ( URI endpoint , String bucket , ClientConfiguration clientConfig ) { try { StringBuilder conbinedEndpoint = new StringBuilder ( ) ; conbinedEndpoint . append ( String . format ( "%s://" , endpoint . getScheme ( ) ) ) ; conbinedEndpoint . append ( buildCanonicalHost ( endpoint , bucket , clientConfig ) ) ; conbinedEndpoint . append ( endpoint . getPort ( ) != - 1 ? String . format ( ":%s" , endpoint . getPort ( ) ) : "" ) ; conbinedEndpoint . append ( endpoint . getPath ( ) ) ; return new URI ( conbinedEndpoint . toString ( ) ) ; } catch ( URISyntaxException ex ) { throw new IllegalArgumentException ( ex . getMessage ( ) , ex ) ; } }
target:  Make a third-level domain by appending bucket name to front of original endpoint  if no binding to CNAME, otherwise use original endpoint as second-level domain directly.