code: public static String[] appendToAll(String append, String[] appendTo) {
          if (append == null) {
              throw new IllegalArgumentException("Method argument append must not be null.");
          }
          if (appendTo == null) {
              throw new IllegalArgumentException("Method argument to must not be null.");
          }
  
          String[] result = new String[appendTo.length];
          for (int i = 0; i  < appendTo.length; ++i) {
              result[i] = appendTo[i] == null ? null : appendTo[i] + append;
          }
  
          return result;
      }
docs: Appends the given String to all elements of the given array.
  
  @param append must not be <code>null</code>.
  @param appendTo must not be <code>null</code>.
  
  @return a new array with all elements of the old array concatenated with the given string.