@Override
    public void write(TensorModifyUpdate update) {
        throw new IllegalArgumentException("Write of TensorModifyUpdate not implemented for this document format version");
    }
Write out the value of weighted set field

@param field - field description (name and data type)
@param ws    - field value
document/src/main/java/com/yahoo/document/serialization/VespaDocumentSerializer6.java