Stores the serialised form of value at data. data should be large enough. See Variant.getSize.
The stored data is in machine native byte order but may not be in fully-normalised form if read from an untrusted source. See Variant.getNormalForm for a solution.
As with Variant.getData, to be able to deserialise the serialised variant successfully, its type and (if the destination machine might be different) its endianness must also be available.
This function is approximately O(n) in the size of data.