Return the hash of the file’s attributes.
Return a hash of the file’s attributes, which is a fingerprint of it. When two files have the same attrHash, it is guaranteed that they have the same attributes (keys, values and types).
Note that the format of the attrHash is not fixed. The only guarantee is that it is a HEX string no longer than 256 bytes (in HEX form).
An example attrHash.