@Override
        public void marshall(Void val, JsonMarshallerContext context, MarshallingInfo<Void> marshallingInfo) {
            throw new IllegalArgumentException(String.format("Parameter '%s' must not be null", marshallingInfo.marshallLocationName()));
        }
Marshallers for Strings bound to a greedy path param. No URL encoding is done on the string
so that it preserves the path structure.
aws-java-sdk-core/src/main/java/com/amazonaws/protocol/json/internal/SimpleTypePathMarshallers.java