async fn update_default_branch(
        &self,
        input: UpdateDefaultBranchInput,
    ) -> Result<(), RusotoError<UpdateDefaultBranchError>> {
        let mut request = self.new_signed_request("POST", "/");
        request.add_header("x-amz-target", "CodeCommit_20150413.UpdateDefaultBranch");
        let encoded = serde_json::to_string(&input).unwrap();
        request.set_payload(Some(encoded));

        let response = self
            .sign_and_dispatch(request, UpdateDefaultBranchError::from_response)
            .await?;
        std::mem::drop(response);
        Ok(())
    }
<p><p>Sets or changes the default branch name for the specified repository.</p> <note> <p>If you use this operation to change the default branch name to the current default branch name, a success message is returned even though the default branch did not change.</p> </note></p>
rusoto/services/codecommit/src/generated.rs