@Provides
  @Singleton
  Datastore getDatastore(@ProjectId String projectId, GoogleCredentials credentials) {
    return DatastoreOptions.newBuilder()
        .setProjectId(projectId)
        .setCredentials(credentials)
        .build()
        .getService();
  }
Return the {@link Environment} we are running in based on our convention of Project ID's ending
in "-" followed by lower-case environment name.

<p>Throws {@link IllegalArgumentException} if projectId does not have a valid environment
suffix.
extensions/cloud/portability-cloud-google/src/main/java/org/datatransferproject/cloud/google/GoogleCloudExtensionModule.java