chore: change branch master to main in github configurations (#1027)

README.md

@@ -468,21 +468,21 @@ see [Assign CPU Resources to Containers](https://kubernetes.io/docs/tasks/config
 
 ## Samples
 
-Samples are in the [`samples/`](https://github.com/googleapis/java-bigtable/tree/master/samples) directory.
+Samples are in the [`samples/`](https://github.com/googleapis/java-bigtable/tree/main/samples) directory.
 
 | Sample                      | Source Code                       | Try it |
 | --------------------------- | --------------------------------- | ------ |
-| Configure Connection Pool | [source code](https://github.com/googleapis/java-bigtable/blob/master/samples/snippets/src/main/java/com/example/bigtable/ConfigureConnectionPool.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigtable&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigtable/ConfigureConnectionPool.java) |
-| Filters | [source code](https://github.com/googleapis/java-bigtable/blob/master/samples/snippets/src/main/java/com/example/bigtable/Filters.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigtable&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigtable/Filters.java) |
-| Hello World | [source code](https://github.com/googleapis/java-bigtable/blob/master/samples/snippets/src/main/java/com/example/bigtable/HelloWorld.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigtable&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigtable/HelloWorld.java) |
-| Instance Admin Example | [source code](https://github.com/googleapis/java-bigtable/blob/master/samples/snippets/src/main/java/com/example/bigtable/InstanceAdminExample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigtable&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigtable/InstanceAdminExample.java) |
-| Quickstart | [source code](https://github.com/googleapis/java-bigtable/blob/master/samples/snippets/src/main/java/com/example/bigtable/Quickstart.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigtable&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigtable/Quickstart.java) |
-| Reads | [source code](https://github.com/googleapis/java-bigtable/blob/master/samples/snippets/src/main/java/com/example/bigtable/Reads.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigtable&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigtable/Reads.java) |
-| Table Admin Example | [source code](https://github.com/googleapis/java-bigtable/blob/master/samples/snippets/src/main/java/com/example/bigtable/TableAdminExample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigtable&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigtable/TableAdminExample.java) |
-| Write Batch | [source code](https://github.com/googleapis/java-bigtable/blob/master/samples/snippets/src/main/java/com/example/bigtable/WriteBatch.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigtable&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigtable/WriteBatch.java) |
-| Write Conditionally | [source code](https://github.com/googleapis/java-bigtable/blob/master/samples/snippets/src/main/java/com/example/bigtable/WriteConditionally.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigtable&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigtable/WriteConditionally.java) |
-| Write Increment | [source code](https://github.com/googleapis/java-bigtable/blob/master/samples/snippets/src/main/java/com/example/bigtable/WriteIncrement.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigtable&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigtable/WriteIncrement.java) |
-| Write Simple | [source code](https://github.com/googleapis/java-bigtable/blob/master/samples/snippets/src/main/java/com/example/bigtable/WriteSimple.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigtable&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigtable/WriteSimple.java) |
+| Configure Connection Pool | [source code](https://github.com/googleapis/java-bigtable/blob/main/samples/snippets/src/main/java/com/example/bigtable/ConfigureConnectionPool.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigtable&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigtable/ConfigureConnectionPool.java) |
+| Filters | [source code](https://github.com/googleapis/java-bigtable/blob/main/samples/snippets/src/main/java/com/example/bigtable/Filters.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigtable&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigtable/Filters.java) |
+| Hello World | [source code](https://github.com/googleapis/java-bigtable/blob/main/samples/snippets/src/main/java/com/example/bigtable/HelloWorld.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigtable&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigtable/HelloWorld.java) |
+| Instance Admin Example | [source code](https://github.com/googleapis/java-bigtable/blob/main/samples/snippets/src/main/java/com/example/bigtable/InstanceAdminExample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigtable&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigtable/InstanceAdminExample.java) |
+| Quickstart | [source code](https://github.com/googleapis/java-bigtable/blob/main/samples/snippets/src/main/java/com/example/bigtable/Quickstart.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigtable&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigtable/Quickstart.java) |
+| Reads | [source code](https://github.com/googleapis/java-bigtable/blob/main/samples/snippets/src/main/java/com/example/bigtable/Reads.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigtable&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigtable/Reads.java) |
+| Table Admin Example | [source code](https://github.com/googleapis/java-bigtable/blob/main/samples/snippets/src/main/java/com/example/bigtable/TableAdminExample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigtable&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigtable/TableAdminExample.java) |
+| Write Batch | [source code](https://github.com/googleapis/java-bigtable/blob/main/samples/snippets/src/main/java/com/example/bigtable/WriteBatch.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigtable&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigtable/WriteBatch.java) |
+| Write Conditionally | [source code](https://github.com/googleapis/java-bigtable/blob/main/samples/snippets/src/main/java/com/example/bigtable/WriteConditionally.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigtable&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigtable/WriteConditionally.java) |
+| Write Increment | [source code](https://github.com/googleapis/java-bigtable/blob/main/samples/snippets/src/main/java/com/example/bigtable/WriteIncrement.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigtable&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigtable/WriteIncrement.java) |
+| Write Simple | [source code](https://github.com/googleapis/java-bigtable/blob/main/samples/snippets/src/main/java/com/example/bigtable/WriteSimple.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-bigtable&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/bigtable/WriteSimple.java) |
 
 
 
@@ -591,10 +591,10 @@ Java is a registered trademark of Oracle and/or its affiliates.
 [developer-console]: https://console.developers.google.com/
 [create-project]: https://cloud.google.com/resource-manager/docs/creating-managing-projects
 [cloud-sdk]: https://cloud.google.com/sdk/
-[troubleshooting]: https://github.com/googleapis/google-cloud-common/blob/master/troubleshooting/readme.md#troubleshooting
-[contributing]: https://github.com/googleapis/java-bigtable/blob/master/CONTRIBUTING.md
-[code-of-conduct]: https://github.com/googleapis/java-bigtable/blob/master/CODE_OF_CONDUCT.md#contributor-code-of-conduct
-[license]: https://github.com/googleapis/java-bigtable/blob/master/LICENSE
+[troubleshooting]: https://github.com/googleapis/google-cloud-common/blob/main/troubleshooting/readme.md#troubleshooting
+[contributing]: https://github.com/googleapis/java-bigtable/blob/main/CONTRIBUTING.md
+[code-of-conduct]: https://github.com/googleapis/java-bigtable/blob/main/CODE_OF_CONDUCT.md#contributor-code-of-conduct
+[license]: https://github.com/googleapis/java-bigtable/blob/main/LICENSE
 
 [enable-api]: https://console.cloud.google.com/flows/enableapi?apiid=bigtable.googleapis.com
 [libraries-bom]: https://github.com/GoogleCloudPlatform/cloud-opensource-java/wiki/The-Google-Cloud-Platform-Libraries-BOM