Currently the java-client only supports byte[] in the category of primitive arrays. This was implemented by a user in #4507.
The server-side, barrage-java-client, and flight-only client, each support arrays of all primitive types. They support arbitrarily nested arrays of primitives (e.g. int[][][]).
The java-client should support all primitive array types and nested primitive arrays. See the UnsupportedOperationException from here: https://github.com/deephaven/deephaven-core/blob/main/java-client/flight/src/main/java/io/deephaven/client/impl/FieldAdapter.java#L135