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

…a to 2.18.1 (#303)

- [ ] 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-channel/google-cloud-channel/src/main/java/com/google/cloud/channel/v1/CloudChannelServiceClient.java

@@ -18,7 +18,6 @@
 
 import com.google.api.core.ApiFuture;
 import com.google.api.core.ApiFutures;
-import com.google.api.core.BetaApi;
 import com.google.api.gax.core.BackgroundResource;
 import com.google.api.gax.longrunning.OperationFuture;
 import com.google.api.gax.paging.AbstractFixedSizeCollection;
@@ -147,7 +146,6 @@ public static final CloudChannelServiceClient create(CloudChannelServiceSettings
    * Constructs an instance of CloudChannelServiceClient, using the given stub for making calls.
    * This is for advanced usage - prefer using create(CloudChannelServiceSettings).
    */
-  @BetaApi("A restructuring of stub classes is planned, so this may break in the future")
   public static final CloudChannelServiceClient create(CloudChannelServiceStub stub) {
     return new CloudChannelServiceClient(stub);
   }
@@ -163,7 +161,6 @@ protected CloudChannelServiceClient(CloudChannelServiceSettings settings) throws
     this.operationsClient = OperationsClient.create(this.stub.getOperationsStub());
   }
 
-  @BetaApi("A restructuring of stub classes is planned, so this may break in the future")
   protected CloudChannelServiceClient(CloudChannelServiceStub stub) {
     this.settings = null;
     this.stub = stub;
@@ -174,7 +171,6 @@ public final CloudChannelServiceSettings getSettings() {
     return settings;
   }
 
-  @BetaApi("A restructuring of stub classes is planned, so this may break in the future")
   public CloudChannelServiceStub getStub() {
     return stub;
   }

java-channel/google-cloud-channel/src/main/java/com/google/cloud/channel/v1/stub/CloudChannelServiceStubSettings.java

@@ -1479,7 +1479,6 @@ public UnaryCallSettings<LookupOfferRequest, Offer> lookupOfferSettings() {
     return listSubscribersSettings;
   }
 
-  @BetaApi("A restructuring of stub classes is planned, so this may break in the future")
   public CloudChannelServiceStub createStub() throws IOException {
     if (getTransportChannelProvider()
         .getTransportName()