chore(deps): upgrade gapic-generator-java to 2.8.0 and update gax-jav…

…a to 2.18.1 (#515)

- [ ] Regenerate this pull request now.

PiperOrigin-RevId: 450543911

Source-Link: googleapis/googleapis@5528344

Source-Link: https://github.com/googleapis/googleapis-gen/commit/9f6775cab1958982b88967a43e5e806af0f135db
Copy-Tag: eyJwIjoiLmdpdGh1Yi8uT3dsQm90LnlhbWwiLCJoIjoiOWY2Nzc1Y2FiMTk1ODk4MmI4ODk2N2E0M2U1ZTgwNmFmMGYxMzVkYiJ9

java-securitycenter-settings/google-cloud-securitycenter-settings/src/main/java/com/google/cloud/securitycenter/settings/v1beta1/SecurityCenterSettingsServiceClient.java

@@ -134,7 +134,6 @@ public static final SecurityCenterSettingsServiceClient create(
    * Constructs an instance of SecurityCenterSettingsServiceClient, using the given stub for making
    * calls. This is for advanced usage - prefer using create(SecurityCenterSettingsServiceSettings).
    */
-  @BetaApi("A restructuring of stub classes is planned, so this may break in the future")
   public static final SecurityCenterSettingsServiceClient create(
       SecurityCenterSettingsServiceStub stub) {
     return new SecurityCenterSettingsServiceClient(stub);
@@ -152,7 +151,6 @@ protected SecurityCenterSettingsServiceClient(SecurityCenterSettingsServiceSetti
         ((SecurityCenterSettingsServiceStubSettings) settings.getStubSettings()).createStub();
   }
 
-  @BetaApi("A restructuring of stub classes is planned, so this may break in the future")
   protected SecurityCenterSettingsServiceClient(SecurityCenterSettingsServiceStub stub) {
     this.settings = null;
     this.stub = stub;
@@ -162,7 +160,6 @@ public final SecurityCenterSettingsServiceSettings getSettings() {
     return settings;
   }
 
-  @BetaApi("A restructuring of stub classes is planned, so this may break in the future")
   public SecurityCenterSettingsServiceStub getStub() {
     return stub;
   }

java-securitycenter-settings/google-cloud-securitycenter-settings/src/main/java/com/google/cloud/securitycenter/settings/v1beta1/stub/SecurityCenterSettingsServiceStubSettings.java

@@ -325,7 +325,6 @@ public UnaryCallSettings<ResetComponentSettingsRequest, Empty> resetComponentSet
     return listComponentsSettings;
   }
 
-  @BetaApi("A restructuring of stub classes is planned, so this may break in the future")
   public SecurityCenterSettingsServiceStub createStub() throws IOException {
     if (getTransportChannelProvider()
         .getTransportName()