Setting a default update_mask for all log sinks

[According to log sink documentation](https://cloud.google.com/logging/docs/reference/v2/rest/v2/sinks/update)
the api will eventually throw an error if update mask isn't provided. The
default specified here is what the api is currently using when an empty mask
is passed.

google/resource_logging_billing_account_sink.go

@@ -2,6 +2,7 @@ package google
 
 import (
 	"fmt"
+
 	"github.com/hashicorp/terraform/helper/schema"
 )
 
@@ -58,7 +59,8 @@ func resourceLoggingBillingAccountSinkUpdate(d *schema.ResourceData, meta interf
 	sink := expandResourceLoggingSinkForUpdate(d)
 
 	// The API will reject any requests that don't explicitly set 'uniqueWriterIdentity' to true.
-	_, err := config.clientLogging.BillingAccounts.Sinks.Patch(d.Id(), sink).UniqueWriterIdentity(true).Do()
+	_, err := config.clientLogging.BillingAccounts.Sinks.Patch(d.Id(), sink).
+		UpdateMask(defaultLogSinkUpdateMask).UniqueWriterIdentity(true).Do()
 	if err != nil {
 		return err
 	}

google/resource_logging_folder_sink.go

@@ -77,7 +77,8 @@ func resourceLoggingFolderSinkUpdate(d *schema.ResourceData, meta interface{}) e
 	sink.ForceSendFields = append(sink.ForceSendFields, "IncludeChildren")
 
 	// The API will reject any requests that don't explicitly set 'uniqueWriterIdentity' to true.
-	_, err := config.clientLogging.Folders.Sinks.Patch(d.Id(), sink).UniqueWriterIdentity(true).Do()
+	_, err := config.clientLogging.Folders.Sinks.Patch(d.Id(), sink).
+		UpdateMask(defaultLogSinkUpdateMask).UniqueWriterIdentity(true).Do()
 	if err != nil {
 		return err
 	}

google/resource_logging_organization_sink.go

@@ -77,7 +77,8 @@ func resourceLoggingOrganizationSinkUpdate(d *schema.ResourceData, meta interfac
 	sink.ForceSendFields = append(sink.ForceSendFields, "IncludeChildren")
 
 	// The API will reject any requests that don't explicitly set 'uniqueWriterIdentity' to true.
-	_, err := config.clientLogging.Organizations.Sinks.Patch(d.Id(), sink).UniqueWriterIdentity(true).Do()
+	_, err := config.clientLogging.Organizations.Sinks.Patch(d.Id(), sink).
+		UpdateMask(defaultLogSinkUpdateMask).UniqueWriterIdentity(true).Do()
 	if err != nil {
 		return err
 	}

google/resource_logging_project_sink.go

@@ -84,7 +84,8 @@ func resourceLoggingProjectSinkUpdate(d *schema.ResourceData, meta interface{})
 	sink := expandResourceLoggingSinkForUpdate(d)
 	uniqueWriterIdentity := d.Get("unique_writer_identity").(bool)
 
-	_, err := config.clientLogging.Projects.Sinks.Patch(d.Id(), sink).UniqueWriterIdentity(uniqueWriterIdentity).Do()
+	_, err := config.clientLogging.Projects.Sinks.Patch(d.Id(), sink).
+		UpdateMask(defaultLogSinkUpdateMask).UniqueWriterIdentity(uniqueWriterIdentity).Do()
 	if err != nil {
 		return err
 	}

google/resource_logging_sink.go

@@ -5,6 +5,9 @@ import (
 	"google.golang.org/api/logging/v2"
 )
 
+// Empty update masks will eventually cause updates to fail, currently empty masks default to this string
+const defaultLogSinkUpdateMask = "destination,filter,includeChildren"
+
 func resourceLoggingSinkSchema() map[string]*schema.Schema {
 	return map[string]*schema.Schema{
 		"name": {

website/docs/r/logging_project_sink.html.markdown

@@ -14,8 +14,9 @@ Manages a project-level logging sink. For more information see
 and
 [API](https://cloud.google.com/logging/docs/reference/v2/rest/).
 
-Note that you must have the "Logs Configuration Writer" IAM role (`roles/logging.configWriter`)
-granted to the credentials used with terraform.
+~> **Note:** You must have [granted the "Logs Configuration Writer"](https://cloud.google.com/logging/docs/access-control) IAM role (`roles/logging.configWriter`) to the credentials used with terraform.
+
+~> **Note** You must [enable the Cloud Resource Manager API](https://console.cloud.google.com/apis/library/cloudresourcemanager.googleapis.com)
 
 ## Example Usage