@Nullable open static fun <T : Any> singleResult(@Nullable results: MutableCollection<T>): T
Return a single result object from the given Collection.
Returns null if 0 result objects found; throws an exception if more than 1 element found.
results - the result Collection (can be null)
IncorrectResultSizeDataAccessException - if more than one element has been found in the given Collection
Return
the single result object, or null if none