feat: promote to GA (#196)

Release-As: 1.0.0

Author: chingor13

.repo-metadata.json

@@ -5,7 +5,7 @@
   "client_documentation": "https://googleapis.dev/java/google-cloud-bigquerydatatransfer/latest",
   "api_description": "transfers data from partner SaaS applications to Google BigQuery on a scheduled, managed basis.",
   "issue_tracker": "https://issuetracker.google.com/savedsearches/559654",
-  "release_level": "beta",
+  "release_level": "ga",
   "language": "java",
   "repo": "googleapis/java-bigquerydatatransfer",
   "repo_short": "java-bigquerydatatransfer",

README.md

@@ -8,9 +8,6 @@ Java idiomatic client for [BigQuery Data Transfer Service][product-docs].
 - [Product Documentation][product-docs]
 - [Client Library Documentation][javadocs]
 
-> Note: This client is a work-in-progress, and may occasionally
-> make backwards-incompatible changes.
-
 ## Quickstart
 
 If you are using Maven with [BOM][libraries-bom], add this to your pom.xml file
@@ -118,9 +115,6 @@ Java 7 or above is required for using this client.
 This library follows [Semantic Versioning](http://semver.org/).
 
 
-It is currently in major version zero (``0.y.z``), which means that anything may change at any time
-and the public API should not be considered stable.
-
 ## Contributing
 
 
@@ -158,7 +152,7 @@ Java 11 | [![Kokoro CI][kokoro-badge-image-5]][kokoro-badge-link-5]
 [kokoro-badge-link-4]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-bigquerydatatransfer/java8-win.html
 [kokoro-badge-image-5]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-bigquerydatatransfer/java11.svg
 [kokoro-badge-link-5]: http://storage.googleapis.com/cloud-devrel-public/java/badges/java-bigquerydatatransfer/java11.html
-[stability-image]: https://img.shields.io/badge/stability-beta-yellow
+[stability-image]: https://img.shields.io/badge/stability-ga-green
 [maven-version-image]: https://img.shields.io/maven-central/v/com.google.cloud/google-cloud-bigquerydatatransfer.svg
 [maven-version-link]: https://search.maven.org/search?q=g:com.google.cloud%20AND%20a:google-cloud-bigquerydatatransfer&core=gav
 [authentication]: https://github.com/googleapis/google-cloud-java#authentication