consumption of method_signature annotation doesn't account for dot-notation access of nested fields for a required field

[noahdietz]

The following code:

gapic-generator-php/src/Generation/BuildMethodFragmentGenerator.php

Lines 135 to 141 in 277c703

	if (count($methodSignatureArguments) !== $requiredFields->count()) {
	throw new \LogicException(sprintf(
	'missing method signature arguments (Expected "%s", found %s)',
	$methodSignature,
	implode(',', $requiredFields->map(fn ($f) => $f->name)->toArray()) ?: 'none'
	));
	}

Does not account for a signature like "foo.a,foo.b" where foo is a google.api.field_behavior = REQUIRED field. The presence of foo.a should be sufficient.

Furthermore, we need to make sure that build fragment generation can handle a dot-notation signature!

[noahdietz]

Note: the only example of this atm is an api in private preview, so testing of the generator with that proto uncovered this.

Technically, nested fields in signatures is allowed per AIP-4232