A Modest Proposal that will never be implemented: add an interface to String, Boolean, Integer, Long, Float and Double. Because all these types already implement "toString" (and I believe their toString representations are compatible with JSON), it can be a pure marker interface.

For the "quick one-off script" case (where Implicitly Declared Classes shine), I think the most galling ceremony in this example is explicitly converting all N items in a list of literals into JsonValues for JsonArray.

This would help a lot:

    public interface JsonArray extends JsonValue {
        static JsonArray of(JsonValue... elements) { ... }
        static JsonArray of(String... elements) { ... }
        static JsonArray of(Double... elements) { ... }
        static JsonArray of(Integer... elements) { ... }
        static JsonArray of(Boolean... elements) { ... }
    }

Then, you could at least write:

    IO.println(JsonObject.of(Map.of("providers",
        JsonArray.of("SUN", "SunRsaSign", "SunEC"))));

And for JsonObject, a little fluent builder API would probably knock out a lot of ceremony, too.

    JsonObject json = JsonObject.builder()
        .put("name", "John")
        .put("age", 30)
        .put("active", true)
        .put("providers", JsonArray.of("SUN", "SunEC"))
        .build();

The alternative today looks quite ceremonious:

    JsonObject json= JsonObject.of(Map.of(
        "name", JsonString("John"),
        "age", JsonNumber(30),
        "active", JsonBoolean(true),
        "providers", JsonArray.of(List.of(
            JsonString("SUN"),
            JsonString("SunRsaSign"),
            JsonString("SunEC")
        ))
    ));