@Nullable
        private static ParameterizedType getParameterizedElementType(Type parameterizedType) {
            if (!(parameterizedType instanceof ParameterizedType)) {
                return null;
            }

            try {
                final Type elementType =
                        ((ParameterizedType) parameterizedType).getActualTypeArguments()[0];
                if (elementType instanceof ParameterizedType) {
                    return (ParameterizedType) elementType;
                }
            } catch (Throwable cause) {
                throw new IllegalArgumentException(
                        "Unsupported parameter type: " + parameterizedType, cause);
            }

            return null;
        }
Sets an {@link AggregationStrategy} for the element.
core/src/main/java/com/linecorp/armeria/internal/server/annotation/AnnotatedValueResolver.java