Retrieves the session corresponding to the specified contextual data (such as a session ID if applicable), or
{@code null} if no Session could be found. If a session is found but invalid (stopped or expired), a
{@link SessionException} will be thrown.
@param key the Session key to use to look-up the Session
@return the {@code Session} instance corresponding to the given lookup key or {@code null} if no session
could be acquired.
@throws SessionException if a session was found but it was invalid (stopped/expired).
Retrieves the session corresponding to the specified contextual data (such as a session ID if applicable), or {@code null} if no Session could be found. If a session is found but invalid (stopped or expired), a {@link SessionException} will be thrown.
@param key the Session key to use to look-up the Session @return the {@code Session} instance corresponding to the given lookup key or {@code null} if no session could be acquired. @throws SessionException if a session was found but it was invalid (stopped/expired).