@Override
    public String toString() {
        return MoreObjects.toStringHelper(this).omitNullValues()
                          .add("annotation",
                               annotationType != null ? annotationType.getSimpleName() : "(none)")
                          .add("httpElementName", httpElementName)
                          .add("pathVariable", isPathVariable)
                          .add("shouldExist", shouldExist)
                          .add("shouldWrapValueAsOptional", shouldWrapValueAsOptional)
                          .add("elementType", elementType.getSimpleName())
                          .add("containerType",
                               containerType != null ? containerType.getSimpleName() : "(none)")
                          .add("defaultValue", defaultValue)
                          .add("defaultValueType",
                               defaultValue != null ? defaultValue.getClass().getSimpleName() : "(none)")
                          .add("description", description)
                          .add("resolver", resolver)
                          .add("enumConverter", enumConverter)
                          .toString();
    }
Returns an attribute resolver which retrieves a value specified by {@code attrKeys}
from the {@link RequestContext}.
core/src/main/java/com/linecorp/armeria/internal/server/annotation/AnnotatedValueResolver.java