Method called to see if a different (or differently configured) key deserializer
is needed to deserialize keys of specified Map property.
Note that instance that this method is called on is typically shared one and
as a result method should NOT
modify this instance but rather construct
and return a new instance. This instance should only be returned as-is, in case
it is already suitable for use.
ctxt Deserialization context to access configuration, additional
deserializers that may be needed by this deserializer
property Method, field or constructor parameter that declared Map for which
contextual instance will be used. Will not be available when deserializing root-level
Map value; otherwise should not be null.
- Key deserializer to use for deserializing keys specified Map property,
may be this instance or a new instance.