default DescriptiveTypeInfoProvider orElse(DescriptiveTypeInfoProvider other) {
        requireNonNull(other, "other");
        return typeDescriptor -> {
            final DescriptiveTypeInfo structInfo = newDescriptiveTypeInfo(typeDescriptor);
            if (structInfo != null) {
                return structInfo;
            } else {
                return other.newDescriptiveTypeInfo(typeDescriptor);
            }
        };
    }
Returns a newly created {@link DescriptiveTypeInfoProvider} that tries this
{@link DescriptiveTypeInfoProvider} first and then the specified {@link DescriptiveTypeInfoProvider}
when the first call returns {@code null}.
core/src/main/java/com/linecorp/armeria/server/docs/DescriptiveTypeInfoProvider.java