Undeclared module dependency for Java 9

[boganiLuca]

Hello, I was using GSON 2.8.6 to save some data received from a device over a TCP connection, using simply
Gson gson = new Gson() return gson.toJson(this);
to serialize my custom class (and then save it into a text file), and
gson.fromJson(input, Analysis.class);
to de-serialize the saved file, so no special configuration or custom serialization involved.
The issue appeared when I built a custom JRE9 using jdeps and jlink and ran my program using that JRE9: when deserializing, I got the exception
Caused by: java.lang.UnsupportedOperationException: Cannot allocate class LocalDateTime at com.google.gson.internal.UnsafeAllocator$4.newInstance(UnsafeAllocator.java:104) at com.google.gson.internal.ConstructorConstructor$14.construct(ConstructorConstructor.java:225) ... 88 common frames omitted
I implemented a custom de-serializer for the classes that caused the exception (just two, LocalDateTime and a custom class), and the issue was solved, but, as was pointed out here , seems that there's an undeclared dependence on the module 'jdk.unsupported' that throws this exception.
Probably it's not a major issue, but I thought you'd like to know. Let me know if you need more code or details

[Marcono1234]

As pointed out in Nicolai's answer on StackOverflow, Gson should declare a dependency on the jdk.unsupported module which contains Unsafe. However, he suggests an optional dependency (requires static).

The question is whether a regular dependency should be used since Gson's functionality is apparently limited without Unsafe. The jdk.unsupported module seems to be pretty small, so the module size should not be a problem.

Edit: Though apparently not everyone wants to use or can use Unsafe, see #445.
Edit 2: Nicolai's answer:

This should be discussed on the GSON issue. Short answer: The presence of jdk.unsupported should not be relied upon (notice its name) and since GSON works without it (just not as comfortable), avoiding a strict dependency would be a good choice IMO.

[Marcono1234]

@inder123, what are your thoughts? Should Gson only declare an optional dependency on jdk.unsupported and then mention in the README / user guide that users should add the module jdk.unsupported at runtime if they want support for Unsafe-based initialization? This would then also allow fixing #445 at a later point.