diff --git a/docs/dyn/appengine_v1.apps.domainMappings.html b/docs/dyn/appengine_v1.apps.domainMappings.html
index ad2f339895c..b2ffa7bcd81 100644
--- a/docs/dyn/appengine_v1.apps.domainMappings.html
+++ b/docs/dyn/appengine_v1.apps.domainMappings.html
@@ -310,7 +310,7 @@ <h3>Method Details</h3>
   },
 }
 
-  updateMask: string, Standard field mask for the set of fields to be updated.
+  updateMask: string, Required. Standard field mask for the set of fields to be updated.
   x__xgafv: string, V1 error format.
     Allowed values
       1 - v1 error format
diff --git a/docs/dyn/appengine_v1.apps.html b/docs/dyn/appengine_v1.apps.html
index 1e441b932b3..1510cc16134 100644
--- a/docs/dyn/appengine_v1.apps.html
+++ b/docs/dyn/appengine_v1.apps.html
@@ -284,7 +284,7 @@ <h3>Method Details</h3>
   &quot;servingStatus&quot;: &quot;A String&quot;, # Serving status of this application.
 }
 
-  updateMask: string, Standard field mask for the set of fields to be updated.
+  updateMask: string, Required. Standard field mask for the set of fields to be updated.
   x__xgafv: string, V1 error format.
     Allowed values
       1 - v1 error format
diff --git a/docs/dyn/appengine_v1.apps.services.html b/docs/dyn/appengine_v1.apps.services.html
index 23977d7364a..8a2126f8257 100644
--- a/docs/dyn/appengine_v1.apps.services.html
+++ b/docs/dyn/appengine_v1.apps.services.html
@@ -244,7 +244,7 @@ <h3>Method Details</h3>
 }
 
   migrateTraffic: boolean, Set to true to gradually shift traffic to one or more versions that you specify. By default, traffic is shifted immediately. For gradual traffic migration, the target versions must be located within instances that are configured for both warmup requests (https://cloud.google.com/appengine/docs/admin-api/reference/rest/v1/apps.services.versions#InboundServiceType) and automatic scaling (https://cloud.google.com/appengine/docs/admin-api/reference/rest/v1/apps.services.versions#AutomaticScaling). You must specify the shardBy (https://cloud.google.com/appengine/docs/admin-api/reference/rest/v1/apps.services#ShardBy) field in the Service resource. Gradual traffic migration is not supported in the App Engine flexible environment. For examples, see Migrating and Splitting Traffic (https://cloud.google.com/appengine/docs/admin-api/migrating-splitting-traffic).
-  updateMask: string, Standard field mask for the set of fields to be updated.
+  updateMask: string, Required. Standard field mask for the set of fields to be updated.
   x__xgafv: string, V1 error format.
     Allowed values
       1 - v1 error format
diff --git a/docs/dyn/appengine_v1alpha.apps.domainMappings.html b/docs/dyn/appengine_v1alpha.apps.domainMappings.html
index c390585f24b..64176c42526 100644
--- a/docs/dyn/appengine_v1alpha.apps.domainMappings.html
+++ b/docs/dyn/appengine_v1alpha.apps.domainMappings.html
@@ -308,7 +308,7 @@ <h3>Method Details</h3>
 }
 
   noManagedCertificate: boolean, Whether a managed certificate should be provided by App Engine. If true, a certificate ID must be manually set in the DomainMapping resource to configure SSL for this domain. If false, a managed certificate will be provisioned and a certificate ID will be automatically populated. Only applicable if ssl_settings.certificate_id is specified in the update mask.
-  updateMask: string, Standard field mask for the set of fields to be updated.
+  updateMask: string, Required. Standard field mask for the set of fields to be updated.
   x__xgafv: string, V1 error format.
     Allowed values
       1 - v1 error format
diff --git a/docs/dyn/appengine_v1beta.apps.domainMappings.html b/docs/dyn/appengine_v1beta.apps.domainMappings.html
index 27bbe2823a6..d612e9979cd 100644
--- a/docs/dyn/appengine_v1beta.apps.domainMappings.html
+++ b/docs/dyn/appengine_v1beta.apps.domainMappings.html
@@ -310,7 +310,7 @@ <h3>Method Details</h3>
   },
 }
 
-  updateMask: string, Standard field mask for the set of fields to be updated.
+  updateMask: string, Required. Standard field mask for the set of fields to be updated.
   x__xgafv: string, V1 error format.
     Allowed values
       1 - v1 error format
diff --git a/docs/dyn/appengine_v1beta.apps.html b/docs/dyn/appengine_v1beta.apps.html
index 0f057715c32..9b7186415fe 100644
--- a/docs/dyn/appengine_v1beta.apps.html
+++ b/docs/dyn/appengine_v1beta.apps.html
@@ -284,7 +284,7 @@ <h3>Method Details</h3>
   &quot;servingStatus&quot;: &quot;A String&quot;, # Serving status of this application.
 }
 
-  updateMask: string, Standard field mask for the set of fields to be updated.
+  updateMask: string, Required. Standard field mask for the set of fields to be updated.
   x__xgafv: string, V1 error format.
     Allowed values
       1 - v1 error format
diff --git a/docs/dyn/appengine_v1beta.apps.services.html b/docs/dyn/appengine_v1beta.apps.services.html
index 5c9dc4cd174..f12977b9eb4 100644
--- a/docs/dyn/appengine_v1beta.apps.services.html
+++ b/docs/dyn/appengine_v1beta.apps.services.html
@@ -244,7 +244,7 @@ <h3>Method Details</h3>
 }
 
   migrateTraffic: boolean, Set to true to gradually shift traffic to one or more versions that you specify. By default, traffic is shifted immediately. For gradual traffic migration, the target versions must be located within instances that are configured for both warmup requests (https://cloud.google.com/appengine/docs/admin-api/reference/rest/v1beta/apps.services.versions#InboundServiceType) and automatic scaling (https://cloud.google.com/appengine/docs/admin-api/reference/rest/v1beta/apps.services.versions#AutomaticScaling). You must specify the shardBy (https://cloud.google.com/appengine/docs/admin-api/reference/rest/v1beta/apps.services#ShardBy) field in the Service resource. Gradual traffic migration is not supported in the App Engine flexible environment. For examples, see Migrating and Splitting Traffic (https://cloud.google.com/appengine/docs/admin-api/migrating-splitting-traffic).
-  updateMask: string, Standard field mask for the set of fields to be updated.
+  updateMask: string, Required. Standard field mask for the set of fields to be updated.
   x__xgafv: string, V1 error format.
     Allowed values
       1 - v1 error format
diff --git a/googleapiclient/discovery_cache/documents/appengine.v1.json b/googleapiclient/discovery_cache/documents/appengine.v1.json
index 90f7af61585..1478fd45e96 100644
--- a/googleapiclient/discovery_cache/documents/appengine.v1.json
+++ b/googleapiclient/discovery_cache/documents/appengine.v1.json
@@ -20,6 +20,7 @@
   "description": "Provisions and manages developers' App Engine applications.",
   "discoveryVersion": "v1",
   "documentationLink": "https://cloud.google.com/appengine/docs/admin-api/",
+  "fullyEncodeReservedExpansion": true,
   "icons": {
     "x16": "http://www.google.com/images/icons/product/search-16.gif",
     "x32": "http://www.google.com/images/icons/product/search-32.gif"
@@ -171,7 +172,7 @@
               "type": "string"
             },
             "updateMask": {
-              "description": "Standard field mask for the set of fields to be updated.",
+              "description": "Required. Standard field mask for the set of fields to be updated.",
               "format": "google-fieldmask",
               "location": "query",
               "type": "string"
@@ -624,7 +625,7 @@
                   "type": "string"
                 },
                 "updateMask": {
-                  "description": "Standard field mask for the set of fields to be updated.",
+                  "description": "Required. Standard field mask for the set of fields to be updated.",
                   "format": "google-fieldmask",
                   "location": "query",
                   "type": "string"
@@ -1140,7 +1141,7 @@
                   "type": "string"
                 },
                 "updateMask": {
-                  "description": "Standard field mask for the set of fields to be updated.",
+                  "description": "Required. Standard field mask for the set of fields to be updated.",
                   "format": "google-fieldmask",
                   "location": "query",
                   "type": "string"
@@ -1594,7 +1595,7 @@
       }
     }
   },
-  "revision": "20210608",
+  "revision": "20210618",
   "rootUrl": "https://appengine.googleapis.com/",
   "schemas": {
     "ApiConfigHandler": {
diff --git a/googleapiclient/discovery_cache/documents/appengine.v1alpha.json b/googleapiclient/discovery_cache/documents/appengine.v1alpha.json
index c75c08f2000..0426b7499cb 100644
--- a/googleapiclient/discovery_cache/documents/appengine.v1alpha.json
+++ b/googleapiclient/discovery_cache/documents/appengine.v1alpha.json
@@ -20,6 +20,7 @@
   "description": "Provisions and manages developers' App Engine applications.",
   "discoveryVersion": "v1",
   "documentationLink": "https://cloud.google.com/appengine/docs/admin-api/",
+  "fullyEncodeReservedExpansion": true,
   "icons": {
     "x16": "http://www.google.com/images/icons/product/search-16.gif",
     "x32": "http://www.google.com/images/icons/product/search-32.gif"
@@ -528,7 +529,7 @@
                   "type": "boolean"
                 },
                 "updateMask": {
-                  "description": "Standard field mask for the set of fields to be updated.",
+                  "description": "Required. Standard field mask for the set of fields to be updated.",
                   "format": "google-fieldmask",
                   "location": "query",
                   "type": "string"
@@ -708,7 +709,7 @@
       }
     }
   },
-  "revision": "20210608",
+  "revision": "20210618",
   "rootUrl": "https://appengine.googleapis.com/",
   "schemas": {
     "AuthorizedCertificate": {
diff --git a/googleapiclient/discovery_cache/documents/appengine.v1beta.json b/googleapiclient/discovery_cache/documents/appengine.v1beta.json
index 511293c5902..c3fa6208b59 100644
--- a/googleapiclient/discovery_cache/documents/appengine.v1beta.json
+++ b/googleapiclient/discovery_cache/documents/appengine.v1beta.json
@@ -20,6 +20,7 @@
   "description": "Provisions and manages developers' App Engine applications.",
   "discoveryVersion": "v1",
   "documentationLink": "https://cloud.google.com/appengine/docs/admin-api/",
+  "fullyEncodeReservedExpansion": true,
   "icons": {
     "x16": "http://www.google.com/images/icons/product/search-16.gif",
     "x32": "http://www.google.com/images/icons/product/search-32.gif"
@@ -171,7 +172,7 @@
               "type": "string"
             },
             "updateMask": {
-              "description": "Standard field mask for the set of fields to be updated.",
+              "description": "Required. Standard field mask for the set of fields to be updated.",
               "format": "google-fieldmask",
               "location": "query",
               "type": "string"
@@ -624,7 +625,7 @@
                   "type": "string"
                 },
                 "updateMask": {
-                  "description": "Standard field mask for the set of fields to be updated.",
+                  "description": "Required. Standard field mask for the set of fields to be updated.",
                   "format": "google-fieldmask",
                   "location": "query",
                   "type": "string"
@@ -1140,7 +1141,7 @@
                   "type": "string"
                 },
                 "updateMask": {
-                  "description": "Standard field mask for the set of fields to be updated.",
+                  "description": "Required. Standard field mask for the set of fields to be updated.",
                   "format": "google-fieldmask",
                   "location": "query",
                   "type": "string"
@@ -1594,7 +1595,7 @@
       }
     }
   },
-  "revision": "20210608",
+  "revision": "20210618",
   "rootUrl": "https://appengine.googleapis.com/",
   "schemas": {
     "ApiConfigHandler": {