question: @ CheckReturnValue @ Nonnull static public String arrayToString ( @ Nonnull byte [ ] v ) { StringBuilder retval = new StringBuilder ( ) ; boolean first = true ; for ( byte e : v ) { if ( ! first ) { retval . append ( ',' ) ; } first = false ; retval . append ( '[' ) ; retval . append ( e ) ; retval . append ( ']' ) ; } return new String ( retval ) ; }
target:  Convert an array of bytes into a single string. Each element is displayed within square brackets and separated by commas.