question: @ Deprecated public static String join ( String delimiter , String ... parts ) { if ( delimiter == null ) { throw new IllegalArgumentException ( "First argument can't be null." ) ; } StringBuilder sb = new StringBuilder ( ) ; for ( String alias : parts ) { if ( sb . length ( ) != 0 ) { sb . append ( delimiter ) ; } sb . append ( alias ) ; } return sb . toString ( ) ; }
target:  Returns a string containing the string representation of each of parts, using configured separator between each.