Document that other JVM languages are not fully supported
Description
Gson's main focus is on Java. Because Gson uses reflection it works in many cases also for other JVM languages such as Kotlin or Scala, but because it does not explicitly consider these languages, language-specific features which do not exist in Java don't work properly. See for example issues with https://github.com/google/gson/labels/kotlin label.
Therefore this pull request adds a warning to prevent new users from investing a lot of time to use Gson with these languages just to notice in the end that it is not properly working or error-prone.
If at some point in the future Gson properly supports other JVM languages, the warning can be removed again. But (at least to me) it seems a bit unlikely that this will ever happen, because:
Gson is in maintenance mode
Additional code and dependencies (or a separate module) is needed to account for these language-specific features
It could cause confusion if new API is added to Gson which is only relevant for other JVM languages but not Java (and the other way around)
There are already mature other JSON libraries for these languages, so Gson would then just compete with them
Actually this limitation mostly (or only) applies to reflection-based serialization and deserialization. Using only custom TypeAdapters, JsonElement (and subclasses) or JsonReader and JsonWriter will probably work fine. However, explaining this might be a bit verbose, and most likely using reflection-based serialization is the most common use case. And even if users initially only use the non-reflective features, they might in the future use them and would then either have to migrate or mix multiple JSON libraries which often does not work that well.
Feedback regarding the wording and where to document this (e.g. not in the README but instead somewhere else) is appreciated. I did not want to explicitly list the other JSON libraries because there are multiple and to not endorse specific ones when there are other ones which might be better suited for the specific use case of the user, or if new libraries emerge in the future.
Purpose
Document that other JVM languages are not fully supported
Description
Gson's main focus is on Java. Because Gson uses reflection it works in many cases also for other JVM languages such as Kotlin or Scala, but because it does not explicitly consider these languages, language-specific features which do not exist in Java don't work properly. See for example issues with https://github.com/google/gson/labels/kotlin label.
Therefore this pull request adds a warning to prevent new users from investing a lot of time to use Gson with these languages just to notice in the end that it is not properly working or error-prone. If at some point in the future Gson properly supports other JVM languages, the warning can be removed again. But (at least to me) it seems a bit unlikely that this will ever happen, because:
Actually this limitation mostly (or only) applies to reflection-based serialization and deserialization. Using only custom
TypeAdapters,JsonElement(and subclasses) orJsonReaderandJsonWriterwill probably work fine. However, explaining this might be a bit verbose, and most likely using reflection-based serialization is the most common use case. And even if users initially only use the non-reflective features, they might in the future use them and would then either have to migrate or mix multiple JSON libraries which often does not work that well.Feedback regarding the wording and where to document this (e.g. not in the README but instead somewhere else) is appreciated. I did not want to explicitly list the other JSON libraries because there are multiple and to not endorse specific ones when there are other ones which might be better suited for the specific use case of the user, or if new libraries emerge in the future.