private static boolean primitiveContent(Inspector cellsValue) {
        if (cellsValue.type() == Type.DOUBLE) return true;
        if (cellsValue.type() == Type.LONG) return true;
        if (cellsValue.type() == Type.ARRAY && cellsValue.entries() > 0 &&
            ( cellsValue.entry(0).type() == Type.DOUBLE || cellsValue.entry(0).type() == Type.LONG)) return true;
        return false;
    }
Deserializes the given tensor from JSON format
vespajlib/src/main/java/com/yahoo/tensor/serialization/JsonFormat.java