The request for
ListSessions][google.spanner.v1.Spanner.ListSessions].
Number of sessions to be returned in the response. If 0 or
less, defaults to the server's maximum allowed page size.
An expression for filtering the results of the request. Filter
rules are case insensitive. The fields eligible for filtering
are: - labels.key where key is the name of a label Some
examples of using filters are: - labels.env:* --> The
session has the label "env". - labels.env:dev --> The
session has the label "env" and the value of the label
contains the string "dev".
