private static void decodeSingleDimensionBlock(String key, Inspector value, MixedTensor.BoundBuilder mixedBuilder) {
        if (value.type() != Type.ARRAY && value.type() != Type.STRING)
            throw new IllegalArgumentException("Expected an item in a blocks array to be an array, not " + value.type());
        mixedBuilder.block(asAddress(key, mixedBuilder.type().mappedSubtype()),
                           decodeValuesInBlock(value, mixedBuilder));
    }
Decodes a tensor value directly at the root, where the format is decided by the tensor type.
vespajlib/src/main/java/com/yahoo/tensor/serialization/JsonFormat.java