docs: public static String join(Object[] array, String sep, String prefix) {
          if (array == null) {
              return "";
          }
  
          int arraySize = array.length;
  
          if (arraySize == 0) {
              return "";
          }
  
          if (sep == null) {
              sep = "";
          }
  
          if (prefix == null) {
              prefix = "";
          }
  
          StringBuilder buf = new StringBuilder(prefix);
          for (int i = 0; i < arraySize; i++) {
              if (i > 0) {
                  buf.append(sep);
              }
              buf.append(array[i] == null ? "" : array[i]);
          }
          return buf.toString();
      }