fix: Add warning regarding external credential sourcing (#1148)

Author: dazuma

gapic-generator/templates/default/service/client/_config.erb

@@ -46,6 +46,13 @@
 #    *  (`GRPC::Core::Channel`) a gRPC channel with included credentials
 #    *  (`GRPC::Core::ChannelCredentials`) a gRPC credentails object
 #    *  (`nil`) indicating no credentials
+#
+#   Warning: If you accept a credential configuration (JSON file or Hash) from an
+#   external source for authentication to Google Cloud, you must validate it before
+#   providing it to a Google API client library. Providing an unvalidated credential
+#   configuration to Google APIs can compromise the security of your systems and data.
+#   For more information, refer to [Validate credential configurations from external
+#   sources](https://cloud.google.com/docs/authentication/external/externally-sourced-credentials).
 #   @return [::Object]
 # @!attribute [rw] scope
 #   The OAuth scopes

gapic-generator/templates/default/service/rest/client/_config.erb

@@ -44,6 +44,13 @@
 #    *  (`Signet::OAuth2::Client`) A signet oauth2 client object
 #       (see the [signet docs](https://rubydoc.info/gems/signet/Signet/OAuth2/Client))
 #    *  (`nil`) indicating no credentials
+#
+#   Warning: If you accept a credential configuration (JSON file or Hash) from an
+#   external source for authentication to Google Cloud, you must validate it before
+#   providing it to a Google API client library. Providing an unvalidated credential
+#   configuration to Google APIs can compromise the security of your systems and data.
+#   For more information, refer to [Validate credential configurations from external
+#   sources](https://cloud.google.com/docs/authentication/external/externally-sourced-credentials).
 #   @return [::Object]
 # @!attribute [rw] scope
 #   The OAuth scopes

shared/output/ads/googleads/lib/google/ads/google_ads/v15/services/campaign_service/client.rb

@@ -357,6 +357,13 @@ def mutate_campaigns request, options = nil
               #    *  (`GRPC::Core::Channel`) a gRPC channel with included credentials
               #    *  (`GRPC::Core::ChannelCredentials`) a gRPC credentails object
               #    *  (`nil`) indicating no credentials
+              #
+              #   Warning: If you accept a credential configuration (JSON file or Hash) from an
+              #   external source for authentication to Google Cloud, you must validate it before
+              #   providing it to a Google API client library. Providing an unvalidated credential
+              #   configuration to Google APIs can compromise the security of your systems and data.
+              #   For more information, refer to [Validate credential configurations from external
+              #   sources](https://cloud.google.com/docs/authentication/external/externally-sourced-credentials).
               #   @return [::Object]
               # @!attribute [rw] scope
               #   The OAuth scopes

shared/output/cloud/compute_small/lib/google/cloud/compute/v1/addresses/rest/client.rb

@@ -713,6 +713,13 @@ def list request, options = nil
               #    *  (`Signet::OAuth2::Client`) A signet oauth2 client object
               #       (see the [signet docs](https://rubydoc.info/gems/signet/Signet/OAuth2/Client))
               #    *  (`nil`) indicating no credentials
+              #
+              #   Warning: If you accept a credential configuration (JSON file or Hash) from an
+              #   external source for authentication to Google Cloud, you must validate it before
+              #   providing it to a Google API client library. Providing an unvalidated credential
+              #   configuration to Google APIs can compromise the security of your systems and data.
+              #   For more information, refer to [Validate credential configurations from external
+              #   sources](https://cloud.google.com/docs/authentication/external/externally-sourced-credentials).
               #   @return [::Object]
               # @!attribute [rw] scope
               #   The OAuth scopes

shared/output/cloud/compute_small/lib/google/cloud/compute/v1/global_operations/rest/client.rb

@@ -376,6 +376,13 @@ def get request, options = nil
               #    *  (`Signet::OAuth2::Client`) A signet oauth2 client object
               #       (see the [signet docs](https://rubydoc.info/gems/signet/Signet/OAuth2/Client))
               #    *  (`nil`) indicating no credentials
+              #
+              #   Warning: If you accept a credential configuration (JSON file or Hash) from an
+              #   external source for authentication to Google Cloud, you must validate it before
+              #   providing it to a Google API client library. Providing an unvalidated credential
+              #   configuration to Google APIs can compromise the security of your systems and data.
+              #   For more information, refer to [Validate credential configurations from external
+              #   sources](https://cloud.google.com/docs/authentication/external/externally-sourced-credentials).
               #   @return [::Object]
               # @!attribute [rw] scope
               #   The OAuth scopes

shared/output/cloud/compute_small/lib/google/cloud/compute/v1/networks/rest/client.rb

@@ -436,6 +436,13 @@ def remove_peering request, options = nil
               #    *  (`Signet::OAuth2::Client`) A signet oauth2 client object
               #       (see the [signet docs](https://rubydoc.info/gems/signet/Signet/OAuth2/Client))
               #    *  (`nil`) indicating no credentials
+              #
+              #   Warning: If you accept a credential configuration (JSON file or Hash) from an
+              #   external source for authentication to Google Cloud, you must validate it before
+              #   providing it to a Google API client library. Providing an unvalidated credential
+              #   configuration to Google APIs can compromise the security of your systems and data.
+              #   For more information, refer to [Validate credential configurations from external
+              #   sources](https://cloud.google.com/docs/authentication/external/externally-sourced-credentials).
               #   @return [::Object]
               # @!attribute [rw] scope
               #   The OAuth scopes

shared/output/cloud/compute_small/lib/google/cloud/compute/v1/region_instance_group_managers/rest/client.rb

@@ -335,6 +335,13 @@ def resize request, options = nil
               #    *  (`Signet::OAuth2::Client`) A signet oauth2 client object
               #       (see the [signet docs](https://rubydoc.info/gems/signet/Signet/OAuth2/Client))
               #    *  (`nil`) indicating no credentials
+              #
+              #   Warning: If you accept a credential configuration (JSON file or Hash) from an
+              #   external source for authentication to Google Cloud, you must validate it before
+              #   providing it to a Google API client library. Providing an unvalidated credential
+              #   configuration to Google APIs can compromise the security of your systems and data.
+              #   For more information, refer to [Validate credential configurations from external
+              #   sources](https://cloud.google.com/docs/authentication/external/externally-sourced-credentials).
               #   @return [::Object]
               # @!attribute [rw] scope
               #   The OAuth scopes

shared/output/cloud/compute_small/lib/google/cloud/compute/v1/region_operations/rest/client.rb

@@ -568,6 +568,13 @@ def wait request, options = nil
               #    *  (`Signet::OAuth2::Client`) A signet oauth2 client object
               #       (see the [signet docs](https://rubydoc.info/gems/signet/Signet/OAuth2/Client))
               #    *  (`nil`) indicating no credentials
+              #
+              #   Warning: If you accept a credential configuration (JSON file or Hash) from an
+              #   external source for authentication to Google Cloud, you must validate it before
+              #   providing it to a Google API client library. Providing an unvalidated credential
+              #   configuration to Google APIs can compromise the security of your systems and data.
+              #   For more information, refer to [Validate credential configurations from external
+              #   sources](https://cloud.google.com/docs/authentication/external/externally-sourced-credentials).
               #   @return [::Object]
               # @!attribute [rw] scope
               #   The OAuth scopes

shared/output/cloud/grafeas_v1/lib/grafeas/v1/grafeas/client.rb

@@ -1493,6 +1493,13 @@ def list_note_occurrences request, options = nil
         #    *  (`GRPC::Core::Channel`) a gRPC channel with included credentials
         #    *  (`GRPC::Core::ChannelCredentials`) a gRPC credentails object
         #    *  (`nil`) indicating no credentials
+        #
+        #   Warning: If you accept a credential configuration (JSON file or Hash) from an
+        #   external source for authentication to Google Cloud, you must validate it before
+        #   providing it to a Google API client library. Providing an unvalidated credential
+        #   configuration to Google APIs can compromise the security of your systems and data.
+        #   For more information, refer to [Validate credential configurations from external
+        #   sources](https://cloud.google.com/docs/authentication/external/externally-sourced-credentials).
         #   @return [::Object]
         # @!attribute [rw] scope
         #   The OAuth scopes

shared/output/cloud/language_v1/lib/google/cloud/language/v1/language_service/client.rb

@@ -1288,6 +1288,13 @@ def annotate_text request, options = nil
             #    *  (`GRPC::Core::Channel`) a gRPC channel with included credentials
             #    *  (`GRPC::Core::ChannelCredentials`) a gRPC credentails object
             #    *  (`nil`) indicating no credentials
+            #
+            #   Warning: If you accept a credential configuration (JSON file or Hash) from an
+            #   external source for authentication to Google Cloud, you must validate it before
+            #   providing it to a Google API client library. Providing an unvalidated credential
+            #   configuration to Google APIs can compromise the security of your systems and data.
+            #   For more information, refer to [Validate credential configurations from external
+            #   sources](https://cloud.google.com/docs/authentication/external/externally-sourced-credentials).
             #   @return [::Object]
             # @!attribute [rw] scope
             #   The OAuth scopes