feat(pubsub): add simple Publisher builder

src/pubsub/src/lib.rs

@@ -102,14 +102,11 @@ pub mod model_ext {
 ///
 /// ```
 /// # async fn sample() -> anyhow::Result<()> {
-/// use google_cloud_pubsub::client::BasePublisher;
+/// use google_cloud_pubsub::client::Publisher;
 /// use google_cloud_pubsub::model::PubsubMessage;
 ///
-/// // Create a client for creating publishers.
-/// let client = BasePublisher::builder().build().await?;
-///
 /// // Create a publisher that handles batching for a specific topic.
-/// let publisher = client.publisher("projects/my-project/topics/my-topic").build();
+/// let publisher = Publisher::builder("projects/my-project/topics/my-topic").build().await?;
 ///
 /// // Publish several messages.
 /// // The client will automatically batch them in the background.

src/pubsub/src/publisher/base_publisher.rs

@@ -16,8 +16,8 @@ use crate::publisher::publisher::PublisherPartialBuilder;
 
 /// Creates [`Publisher`](super::publisher::Publisher) instances.
 ///
-/// This is the main entry point for the publisher API. A single `BasePublisher`
-/// can be used to create multiple `Publisher` clients for different topics.
+/// A single `BasePublisher` can be used to create multiple `Publisher`
+/// clients for different topics.
 /// It manages the underlying gRPC connection and authentication.
 ///
 /// # Example
@@ -64,6 +64,7 @@ pub type BasePublisherBuilder =
 pub(crate) mod client_builder {
     use super::BasePublisher;
 
+    #[derive(Clone, Debug)]
     pub struct Factory;
     impl gax::client_builder::internal::ClientFactory for Factory {
         type Client = BasePublisher;