private static Type unwrapOptional(Type parameterizedType) {
            // Unwrap once again so that a pattern like 'Optional<List<?>>' can be supported.
            assert parameterizedType instanceof ParameterizedType : String.valueOf(parameterizedType);
            parameterizedType = ((ParameterizedType) parameterizedType).getActualTypeArguments()[0];
            return parameterizedType;
        }
Sets an {@link AggregationStrategy} for the element.
core/src/main/java/com/linecorp/armeria/internal/server/annotation/AnnotatedValueResolver.java