The FilesystemMapInterface defines a contract for managing and retrieving
filesystem instances by their associated names. It provides methods to check
for the existence of a filesystem and to retrieve it when needed. This interface
is useful in scenarios where multiple filesystems are utilized, allowing for
seamless access and management without the need for complex logic.
Implementing classes are responsible for maintaining a mapping between filesystem
names and their corresponding instances, enabling efficient interaction with
various filesystems in a unified manner.