// First clear raw_input, country_code_source and preferred_domestic_carrier_code fields and any
// empty-string extensions so that we can use the proto-buffer equality method.
firstNumber.clearRawInput();
firstNumber.clearCountryCodeSource();
firstNumber.clearPreferredDomesticCarrierCode();
secondNumber.clearRawInput();
secondNumber.clearCountryCodeSource();
secondNumber.clearPreferredDomesticCarrierCode();
if (firstNumber.hasExtension() &&
firstNumber.getExtension().length() == 0) {
firstNumber.clearExtension();