gson-null-safe

Null-safe JSON deserialization with Gson. It's working! Kind of.

The deserialization is done by ReflectiveTypeAdapterFactory included in Gson with checks and fixes done by NullSafeTypeAdapterFactory.

It is not a complete solution because the ReflectiveTypeAdapterFactory is not properly set up. E.g. the excluder is the default one which does not contain the user specified field and class exclusions. There are probably other problems, too.

To use it, register NullSafeTypeAdapterFactory and annotate your classes with either @NullSafeNullable or @NullSafeOptional:

• @NullSafeNullable means that a JsonParseException will be thrown if after deserialization any of the fields are null except for @Nullable annotated fields.
• @NullSafeOptional means that a JsonParseException will be thrown if after deserialization any of the fields are null. You can specify optional fields using the Optional<T> type from Guava, and these fields will be properly populated with Optional.absent() if the JSON had a null value for the given field or it did not contain the field at all.