I'm not sure that @NotNull example is appropriate. Java compiler does not add any checks for @NotNull annotations. Those annotations exist for IDE and linting tools, compiler doesn't care. May be there are Java-like languages like Lombok or non-standard compilers which do add those checks, but I think that Java decompiler shouldn't do assumptions of these additional tools.
A better example for Java would be something like lambda expressions on functional interfaces. There, the compiler is creating an anonymous object that implements the interface. A reversable decompiler will just see the anonymous class instance whereas an analytical decompiler can detect that it is likely a lambda expression due to it being an anonymous class object implementing a single method interface and is being passed to a function argument that takes that interface as a parameter.
In C# yield is implemented as a state machine, so an analytical decompiler could recognise that construct.
And yes, for JVM decompilers it could have language heuristics to detect (or be specifically for) Lombok, Scala, Groovy, Kotlin, etc.
> When you compile your project with IntelliJ IDEA build tool, the IDE adds assertions to all code elements annotated with @NotNull. These assertions will throw an error if the elements happen to be null at runtime.
When using Lombok it will use a compiler plugin for this so maven builds have @nonnull generated as if-statements. I dont know if intellij uses their own plugin but they do support Lombok in maven projects, so maybe thats where this is coming from. Afaik intellij has no built in compiler but relies on java .
I was initially impressed with Lombok and then ran into all the downsides of it and it was institutionally abandoned at one particular firm I was with (100s of devs).
