chore: support for option multiplexed in create session (#2175)

This PR contains addition of an option `multiplexed` enabling which while calling createSession method will create a multiplexed session instead of regular session.

Author: alkatrivedi

src/database.ts

@@ -247,6 +247,7 @@ export interface CreateSessionOptions {
   labels?: {[k: string]: string} | null;
   databaseRole?: string | null;
   gaxOptions?: CallOptions;
+  multiplexed?: boolean;
 }
 
 export interface GetIamPolicyOptions {
@@ -981,6 +982,10 @@ class Database extends common.GrpcServiceObject {
       reqOpts.session.labels = options.labels;
     }
 
+    if (options.multiplexed) {
+      reqOpts.session.multiplexed = options.multiplexed;
+    }
+
     reqOpts.session.creatorRole =
       options.databaseRole || this.databaseRole || null;
 

test/database.ts

@@ -2177,6 +2177,23 @@ describe('Database', () => {
       database.createSession(databaseRole, assert.ifError);
     });
 
+    it('should send multiplexed correctly', done => {
+      const multiplexed = {multiplexed: true};
+      const options = {a: 'b', multiplexed};
+      const originalOptions = extend(true, {}, options);
+
+      database.request = config => {
+        assert.deepStrictEqual(
+          config.reqOpts.session.multiplexed,
+          multiplexed.multiplexed
+        );
+        assert.deepStrictEqual(options, originalOptions);
+        done();
+      };
+
+      database.createSession(multiplexed, assert.ifError);
+    });
+
     describe('error', () => {
       const ERROR = new Error('Error.');
       const API_RESPONSE = {};