code: public static String toDelimitedString(Object[] arr, String delim) {
          if (arr == null || arr.length == 0) {
              return EMPTY;
          }
          if (arr.length == 1) {
              return (arr[0] == null) ? EMPTY : arr[0].toString();
          }
          StringBuilder sb = new StringBuilder();
          for (int i = 0; i < arr.length; i++) {
              if (i > 0) {
                  sb.append(delim);
              }
              sb.append(arr[i]);
          }
          return sb.toString();
      }
docs: Convert a {@code String} array into a delimited {@code String} (e.g. CSV).
  <p>Useful for {@code toString()} implementations.
  
  @param arr the array to display
  @param delim the delimiter to use (typically a ",")
  @return the delimited {@code String}