code: static void formatMessage3(final StringBuilder buffer, final char[] messagePattern, final int patternLength,
              final Object[] arguments, final int argCount, final int[] indices) {
          if (messagePattern == null) {
              return;
          }
          if (arguments == null || argCount == 0) {
              buffer.append(messagePattern);
              return;
          }
          int previous = 0;
          for (int i = 0; i < argCount; i++) {
              buffer.append(messagePattern, previous, indices[i]);
              previous = indices[i] + 2;
              recursiveDeepToString(arguments[i], buffer, null);
          }
          buffer.append(messagePattern, previous, patternLength);
      }
docs: Replace placeholders in the given messagePattern with arguments.
  
  @param buffer the buffer to write the formatted message into
  @param messagePattern the message pattern containing placeholders.
  @param arguments      the arguments to be used to replace placeholders.