Sets an application specific hash value function for the elements of the hash set.
Sets an application specific hash value function for the elements of the hash set. For tree sets this function does nothing.An application specific hash value function can be set to the set only if the set is empty.
The hash function specified should be based on the hash functions supplied by the library: pblSetByteBufferHashValue and pblSetStringHashValue.
If no specific hash value function is specified by the user, the default hash value function pblSetDefaultHashValue is used.
This method has a time complexity of O(1).