Add nonnull annotations for PolarisEntityManager public constructor

[chenjian2664]

No description provided.

[adutra]

@chenjian2664 I'm not sure we want to go in this direction. I think that instead we should assume that in all Polaris code, parameters and return types are non-null by default, and only annotate the nullable ones. WDYT?

[flyrain]

I believe it's appropriate to apply the @Nonnull annotation to these parameters. By checking these fields, they are indeed expected to be non-null. This annotation will make the intent explicit and enhance both code clarity and safety. With that, +1 on the PR.

[chenjian2664]

@adutra Thanks for the reply.

I think that instead we should assume that in all Polaris code, parameters and return types are non-null by default

In this case, explicit check would make code more safe just as @flyrain mentioned.

and only annotate the nullable ones.

The current code base seems do the both the explicit check for null and nonnull in most places

[adutra]

@flyrain and @chenjian2664 I don't mind adding these annotations, but if we think globally about Polaris code, and assuming that, since the API is biased towards non-nullability by default, about 80% of method arguments and method return types are non-null, annotating each and every one of them will quickly become a visual clutter.

Instead, there are better options to mark an API as "non-null by default", e.g. using JSR 305 annotation @ParametersAreNonnullByDefault placed at package level. Most IDEs are capable of understanding that and would automatically enforce non-nullability everywhere.

[dimas-b]

I support using the "non-null by default" convention in APIs.