chore: regens API reference docs (#889)

diff --git a/docs/dyn/appengine_v1beta.apps.domainMappings.html b/docs/dyn/appengine_v1beta.apps.domainMappings.html
index f4b94e5..e1ccdcf 100644
--- a/docs/dyn/appengine_v1beta.apps.domainMappings.html
+++ b/docs/dyn/appengine_v1beta.apps.domainMappings.html
@@ -75,7 +75,7 @@
 <h1><a href="appengine_v1beta.html">App Engine Admin API</a> . <a href="appengine_v1beta.apps.html">apps</a> . <a href="appengine_v1beta.apps.domainMappings.html">domainMappings</a></h1>
 <h2>Instance Methods</h2>
 <p class="toc_element">
-  <code><a href="#create">create(appsId, body, overrideStrategy=None, x__xgafv=None)</a></code></p>
+  <code><a href="#create">create(appsId, body=None, overrideStrategy=None, x__xgafv=None)</a></code></p>
 <p class="firstline">Maps a domain to an application. A user must be authorized to administer a domain in order to map it to an application. For a list of available authorized domains, see AuthorizedDomains.ListAuthorizedDomains.</p>
 <p class="toc_element">
   <code><a href="#delete">delete(appsId, domainMappingsId, x__xgafv=None)</a></code></p>
@@ -90,16 +90,16 @@
   <code><a href="#list_next">list_next(previous_request, previous_response)</a></code></p>
 <p class="firstline">Retrieves the next page of results.</p>
 <p class="toc_element">
-  <code><a href="#patch">patch(appsId, domainMappingsId, body, updateMask=None, x__xgafv=None)</a></code></p>
+  <code><a href="#patch">patch(appsId, domainMappingsId, body=None, updateMask=None, x__xgafv=None)</a></code></p>
 <p class="firstline">Updates the specified domain mapping. To map an SSL certificate to a domain mapping, update certificate_id to point to an AuthorizedCertificate resource. A user must be authorized to administer the associated domain in order to update a DomainMapping resource.</p>
 <h3>Method Details</h3>
 <div class="method">
-    <code class="details" id="create">create(appsId, body, overrideStrategy=None, x__xgafv=None)</code>
+    <code class="details" id="create">create(appsId, body=None, overrideStrategy=None, x__xgafv=None)</code>
   <pre>Maps a domain to an application. A user must be authorized to administer a domain in order to map it to an application. For a list of available authorized domains, see AuthorizedDomains.ListAuthorizedDomains.
 
 Args:
   appsId: string, Part of `parent`. Name of the parent Application resource. Example: apps/myapp. (required)
-  body: object, The request body. (required)
+  body: object, The request body.
     The object takes the form of:
 
 { # A domain serving an App Engine application.
@@ -129,9 +129,6 @@
   An object of the form:
 
     { # This resource represents a long-running operation that is the result of a network API call.
-    "metadata": { # Service-specific metadata associated with the operation. It typically contains progress information and common metadata such as create time. Some services might not provide such metadata. Any method that returns a long-running operation should document the metadata type, if any.
-      "a_key": "", # Properties of the object. Contains field @type with type URL.
-    },
     "error": { # The Status type defines a logical error model that is suitable for different programming environments, including REST APIs and RPC APIs. It is used by gRPC (https://github.com/grpc). Each Status message contains three pieces of data: error code, error message, and error details.You can find out more about this error model and how to work with it in the API Design Guide (https://cloud.google.com/apis/design/errors). # The error result of the operation in case of failure or cancellation.
       "message": "A String", # A developer-facing error message, which should be in English. Any user-facing error message should be localized and sent in the google.rpc.Status.details field, or localized by the client.
       "code": 42, # The status code, which should be an enum value of google.rpc.Code.
@@ -146,6 +143,9 @@
       "a_key": "", # Properties of the object. Contains field @type with type URL.
     },
     "name": "A String", # The server-assigned name, which is only unique within the same service that originally returns it. If you use the default HTTP mapping, the name should be a resource name ending with operations/{unique_id}.
+    "metadata": { # Service-specific metadata associated with the operation. It typically contains progress information and common metadata such as create time. Some services might not provide such metadata. Any method that returns a long-running operation should document the metadata type, if any.
+      "a_key": "", # Properties of the object. Contains field @type with type URL.
+    },
   }</pre>
 </div>
 
@@ -165,9 +165,6 @@
   An object of the form:
 
     { # This resource represents a long-running operation that is the result of a network API call.
-    "metadata": { # Service-specific metadata associated with the operation. It typically contains progress information and common metadata such as create time. Some services might not provide such metadata. Any method that returns a long-running operation should document the metadata type, if any.
-      "a_key": "", # Properties of the object. Contains field @type with type URL.
-    },
     "error": { # The Status type defines a logical error model that is suitable for different programming environments, including REST APIs and RPC APIs. It is used by gRPC (https://github.com/grpc). Each Status message contains three pieces of data: error code, error message, and error details.You can find out more about this error model and how to work with it in the API Design Guide (https://cloud.google.com/apis/design/errors). # The error result of the operation in case of failure or cancellation.
       "message": "A String", # A developer-facing error message, which should be in English. Any user-facing error message should be localized and sent in the google.rpc.Status.details field, or localized by the client.
       "code": 42, # The status code, which should be an enum value of google.rpc.Code.
@@ -182,6 +179,9 @@
       "a_key": "", # Properties of the object. Contains field @type with type URL.
     },
     "name": "A String", # The server-assigned name, which is only unique within the same service that originally returns it. If you use the default HTTP mapping, the name should be a resource name ending with operations/{unique_id}.
+    "metadata": { # Service-specific metadata associated with the operation. It typically contains progress information and common metadata such as create time. Some services might not provide such metadata. Any method that returns a long-running operation should document the metadata type, if any.
+      "a_key": "", # Properties of the object. Contains field @type with type URL.
+    },
   }</pre>
 </div>
 
@@ -272,13 +272,13 @@
 </div>
 
 <div class="method">
-    <code class="details" id="patch">patch(appsId, domainMappingsId, body, updateMask=None, x__xgafv=None)</code>
+    <code class="details" id="patch">patch(appsId, domainMappingsId, body=None, updateMask=None, x__xgafv=None)</code>
   <pre>Updates the specified domain mapping. To map an SSL certificate to a domain mapping, update certificate_id to point to an AuthorizedCertificate resource. A user must be authorized to administer the associated domain in order to update a DomainMapping resource.
 
 Args:
   appsId: string, Part of `name`. Name of the resource to update. Example: apps/myapp/domainMappings/example.com. (required)
   domainMappingsId: string, Part of `name`. See documentation of `appsId`. (required)
-  body: object, The request body. (required)
+  body: object, The request body.
     The object takes the form of:
 
 { # A domain serving an App Engine application.
@@ -308,9 +308,6 @@
   An object of the form:
 
     { # This resource represents a long-running operation that is the result of a network API call.
-    "metadata": { # Service-specific metadata associated with the operation. It typically contains progress information and common metadata such as create time. Some services might not provide such metadata. Any method that returns a long-running operation should document the metadata type, if any.
-      "a_key": "", # Properties of the object. Contains field @type with type URL.
-    },
     "error": { # The Status type defines a logical error model that is suitable for different programming environments, including REST APIs and RPC APIs. It is used by gRPC (https://github.com/grpc). Each Status message contains three pieces of data: error code, error message, and error details.You can find out more about this error model and how to work with it in the API Design Guide (https://cloud.google.com/apis/design/errors). # The error result of the operation in case of failure or cancellation.
       "message": "A String", # A developer-facing error message, which should be in English. Any user-facing error message should be localized and sent in the google.rpc.Status.details field, or localized by the client.
       "code": 42, # The status code, which should be an enum value of google.rpc.Code.
@@ -325,6 +322,9 @@
       "a_key": "", # Properties of the object. Contains field @type with type URL.
     },
     "name": "A String", # The server-assigned name, which is only unique within the same service that originally returns it. If you use the default HTTP mapping, the name should be a resource name ending with operations/{unique_id}.
+    "metadata": { # Service-specific metadata associated with the operation. It typically contains progress information and common metadata such as create time. Some services might not provide such metadata. Any method that returns a long-running operation should document the metadata type, if any.
+      "a_key": "", # Properties of the object. Contains field @type with type URL.
+    },
   }</pre>
 </div>