Invalid JSON from Double.NaN as JsonObject property

[danorton-cubic-austin]

Double.NaN as JsonObject property generates invalid JSON and does not throw exception
This is with 2.8.2
Code fragment:

    final Gson gson = new GsonBuilder().serializeNulls().create();
    JsonObject jsonObject = new JsonObject();
    jsonObject.addProperty("invalidDouble", Double.NaN);
    JsonElement jsonElement = jsonObject;
    log("As property within object: " + jsonElement.toString()); // expect this to throw exception
    jsonElement = new JsonPrimitive(Double.NaN);
    log("As primitive: " + jsonElement.toString());  // expect this to throw exception
    jsonElement = gson.toJsonTree(Double.NaN);
    log("As raw value toJsonTree: " + jsonElement.toString());  // this throws exception, as expected

Output:

As property within object: {"invalidDouble":NaN}
As primitive: NaN
Exception in thread "main" java.lang.IllegalArgumentException: NaN is not a valid double value as per JSON specification. To override this behavior, use GsonBuilder.serializeSpecialFloatingPointValues() method.
	at com.google.gson.Gson.checkValidFloatingPoint(Gson.java:324)
	at com.google.gson.Gson$1.write(Gson.java:292)
	at com.google.gson.Gson$1.write(Gson.java:278)
	at com.google.gson.Gson.toJson(Gson.java:669)
	at com.google.gson.Gson.toJsonTree(Gson.java:562)
	at com.google.gson.Gson.toJsonTree(Gson.java:541)

[danorton-cubic-austin]

Related:

• Exception when deserializing Double.NaN, Double.NEGATIVE_INFINITY and Double.POSITIVE_INFINITY #81 - Exception when deserializing Double.NaN, Double.NEGATIVE_INFINITY and Double.POSITIVE_INFINITY
• Wrong Exception message in case of Double.NaN serialization #498 - Wrong Exception message in case of Double.NaN serialization
• Special FP values serialized without error when using JsonPrimitive (when this option is disabled) #752 - Special FP values serialized without error when using JsonPrimitive (when this option is disabled)

[danorton-cubic-austin]

Is this a result of this PR?

• value(double) can write NaN and infinite values when lenient, as value(Number) does #1093 - value(double) can write NaN and infinite values when lenient, as value(Number) does
  Why is lenient set? How can I unset it?

[danorton-cubic-austin]

See also:

• GsonBuilder.setLenient(false) #372 - GsonBuilder.setLenient(false)

[Marcono1234]

The problem here is that the non-finite floating point value check, which is affected by GsonBuilder.serializeSpecialFloatingPointValues(), only occurs for Float and Double (and the corresponding primitive types). However, any other adapter which directly uses JsonWriter.value(Number) (such as the adapter for JsonElement) is not influenced by this, and is only affected by the lenientness of the JsonWriter. And as mentioned in #372 (and related issues) that writer is unfortunately lenient by default.