public static AppliesTo fromNode(Node node) {
        String value = node.expectStringNode()
                .expectOneOf("client", "server")
                .toUpperCase(Locale.ENGLISH);
        return AppliesTo.valueOf(value);
    }
Indicates that a compliance test case is only to be implemented by
"client" or "server" implementations.
smithy-protocol-test-traits/src/main/java/software/amazon/smithy/protocoltests/traits/AppliesTo.java