public Optional<ShapeId> getErrorId() {
        return Optional.ofNullable(errorId);
    }
Gets the ID of the expected error shape.

<p>If present, it indicates the call should throw a matching error.
Otherwise, the call should throw any error.

@return The ID of the expected error shape.
smithy-smoke-test-traits/src/main/java/software/amazon/smithy/smoketests/traits/FailureExpectation.java