private List<ValidationEvent> validateError(StructureShape shape, HttpBindingIndex bindings) {
        return validatePayload(shape.getId(), shape, bindings, false)
                .map(Collections::singletonList)
                .orElseGet(Collections::emptyList);
    }
Validates that if a payload trait is present then all members of the
input of an operation are bound to part of the message.
smithy-model/src/main/java/software/amazon/smithy/model/validation/validators/HttpPayloadValidator.java