docs: @VisibleForTesting
      String obfuscateConfidentialData(final CharSequence confidentialSequence, @Nullable final CharSequence unmasked) {
          final int maskedLength = unmasked == null ? confidentialSequence.length() : confidentialSequence.length() - unmasked.length();
          return new String(new char[maskedLength]).replace('\0', PAD_CHAR);
      }