@Override
        public List<ValidationEvent> validateScheme(
                Map<Identifier, Literal> authScheme,
                FromSourceLocation sourceLocation,
                BiFunction<FromSourceLocation, String, ValidationEvent> emitter
        ) {
            List<ValidationEvent> events = hasAllKeys(emitter,
                    authScheme,
                    ListUtils.of(RuleSetAuthSchemesValidator.NAME, ID_SIGNING_NAME),
                    sourceLocation);
            validateStringProperty(emitter, authScheme, ID_SIGNING_NAME).ifPresent(events::add);

            // Events are emitted by default as ERROR, but we want to make this viable with acknowledgement.
            ValidationEvent event = emitter.apply(sourceLocation,
                    "Requirements for `sigv4-` auth sub-scheme validation may change.");
            events.add(event.toBuilder().severity(Severity.DANGER).build());

            return events;
        }
Returns if a given auth scheme is equivalent to {@code aws.auth#sigv4a}.

@param authScheme name of the auth scheme.
@return whether the auth scheme is equivalent to {@code aws.auth#sigv4a}.
smithy-aws-endpoints/src/main/java/software/amazon/smithy/rulesengine/aws/language/functions/EndpointAuthUtils.java