delete "return null",delivery deserializer to handle

[ihrthk]

TreeTypeAdapter.java
/**
@OverRide public T read(JsonReader in) throws IOException {
if (deserializer == null) {
return delegate().read(in);
}
JsonElement value = Streams.parse(in);
if (value.isJsonNull()) {
return null;
}
return deserializer.deserialize(value, typeToken.getType(), context);
}
**/

[Marcono1234]

The documentation for the GsonBuilder.registerTypeAdapter method has been adjusted by #1704 and the incorrect behavior when used with @JsonAdapter has been fixed by #1555. I am therefore closing this issue here (especially since it was not mentioned for which use case this behavior caused issues). #852 is still open, and maybe it can also be considered to add new GsonBuilder methods which allow registering JsonSerializer or JsonDeserializer without making them null-safe. For now the workaround is to use TypeAdapter or TypeAdapterFactory instead, if possible.