feat(topologies): expose underlaying `logicalSessionTimeoutMinutes'

NODE-1088

Author: mbroadst

lib/topologies/mongos.js

@@ -266,6 +266,13 @@ Object.defineProperty(Mongos.prototype, 'haInterval', {
   }
 });
 
+Object.defineProperty(Mongos.prototype, 'logicalSessionTimeoutMinutes', {
+  enumerable: true,
+  get: function() {
+    return this.s.coreTopology.logicalSessionTimeoutMinutes;
+  }
+});
+
 // Connect
 Mongos.prototype.connect = function(db, _options, callback) {
   var self = this;

lib/topologies/replset.js

@@ -291,6 +291,13 @@ Object.defineProperty(ReplSet.prototype, 'haInterval', {
   }
 });
 
+Object.defineProperty(ReplSet.prototype, 'logicalSessionTimeoutMinutes', {
+  enumerable: true,
+  get: function() {
+    return this.s.coreTopology.logicalSessionTimeoutMinutes;
+  }
+});
+
 var define = (ReplSet.define = new Define('ReplSet', ReplSet, false));
 
 // Ensure the right read Preference object

lib/topologies/server.js

@@ -288,6 +288,13 @@ Object.defineProperty(Server.prototype, 'port', {
   }
 });
 
+Object.defineProperty(Server.prototype, 'logicalSessionTimeoutMinutes', {
+  enumerable: true,
+  get: function() {
+    return this.s.coreTopology.logicalSessionTimeoutMinutes;
+  }
+});
+
 // Connect
 // Server.prototype.connect = function(db, _options, callback) {
 Server.prototype.connect = function(_options, callback) {