question: public String toUuidString ( ) { String result = String . join ( "-" , contentAsHex ( 0 , 4 ) , contentAsHex ( 4 , 6 ) , contentAsHex ( 6 , 8 ) , contentAsHex ( 8 , 10 ) , contentAsHex ( 10 , 16 ) ) ; return result . toLowerCase ( ) ; }
target:  UUID created from the first 128 bits of SHA256