Protobuf Upgrade to 25.2 has broken V1 GAPIC Generator

[bshaffer]

cl/603226138 has broken the GAPIC generation in the V1 clients (see googleapis/google-cloud-php#7023). Some of the changes that look wrong are:

• All RPC method arguments have been removed
• All sample arguments have been removed
• All setters used in tests have been removed
• References to resource name helpers have been removed in comments

This may be due to changes in the way the GAPIC generator locates google.api.field_behavior, which is done in FieldDetails::determineIsRequired, and is read by ProtoHelpers::getCustomOptionRaw:

gapic-generator-php/src/Utils/ProtoHelpers.php

Lines 351 to 384 in 277c703

	$values = [];
	if ($message->hasOptions()) {
	$opts = $message->getOptions();
	$unknown = $messageUnknown->getValue($opts);
	if ($unknown) {
	$unknownStream = new CodedInputStream($unknown);
	// Read through the stream of all custom options, looking for
	// the requested option-id. If it's repeated, then all options
	// must be parsed, otherwise return the first found.
	while (($tag = $unknownStream->readTag()) !== 0) {
	$value = 0;
	// TODO: Handle extra option types as required.
	switch (GPBWire::getTagWireType($tag)) {
	case GPBWire::WIRETYPE_VARINT:
	$unknownStream->readVarint32($value);
	break;
	case GPBWire::WIRETYPE_LENGTH_DELIMITED:
	$len = 0;
	$unknownStream->readVarintSizeAsInt($len);
	$unknownStream->readRaw($len, $value);
	break;
	default:
	throw new \Exception('Cannot read option tag');
	}
	if (GPBWire::getTagFieldNumber($tag) === $optionId) {
	if ($repeated) {
	$values[] = $value;
	} else {
	return $value;
	}
	}
	}
	}
	}

Note: There may be a way to get options from UPB. However, the APIs would need to be implemented for both the pure-PHP and upb backends. The upb library itself supports it, but there is currently no glue.

UPDATE: We've been able to duplicate the error (which seems to be affecting all "repeated" custom options) by updating the protoc binary to 25.2 and running the following test:

vendor/bin/phpunit tests/Unit/Utils/ --filter testProtoCustomOptions

UPDATE 2 - If we add [packed = false] to the custom option, the previous custom option logic works as expected.