chore: regens API reference docs (#889)

diff --git a/docs/dyn/dialogflow_v2.projects.agent.sessions.contexts.html b/docs/dyn/dialogflow_v2.projects.agent.sessions.contexts.html
index 1fd1390..f7110fb 100644
--- a/docs/dyn/dialogflow_v2.projects.agent.sessions.contexts.html
+++ b/docs/dyn/dialogflow_v2.projects.agent.sessions.contexts.html
@@ -75,7 +75,7 @@
 <h1><a href="dialogflow_v2.html">Dialogflow API</a> . <a href="dialogflow_v2.projects.html">projects</a> . <a href="dialogflow_v2.projects.agent.html">agent</a> . <a href="dialogflow_v2.projects.agent.sessions.html">sessions</a> . <a href="dialogflow_v2.projects.agent.sessions.contexts.html">contexts</a></h1>
 <h2>Instance Methods</h2>
 <p class="toc_element">
-  <code><a href="#create">create(parent, body, x__xgafv=None)</a></code></p>
+  <code><a href="#create">create(parent, body=None, x__xgafv=None)</a></code></p>
 <p class="firstline">Creates a context.</p>
 <p class="toc_element">
   <code><a href="#delete">delete(name, x__xgafv=None)</a></code></p>
@@ -84,41 +84,68 @@
   <code><a href="#get">get(name, x__xgafv=None)</a></code></p>
 <p class="firstline">Retrieves the specified context.</p>
 <p class="toc_element">
-  <code><a href="#list">list(parent, pageSize=None, pageToken=None, x__xgafv=None)</a></code></p>
+  <code><a href="#list">list(parent, pageToken=None, x__xgafv=None, pageSize=None)</a></code></p>
 <p class="firstline">Returns the list of all contexts in the specified session.</p>
 <p class="toc_element">
   <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(name, body, updateMask=None, x__xgafv=None)</a></code></p>
+  <code><a href="#patch">patch(name, body=None, updateMask=None, x__xgafv=None)</a></code></p>
 <p class="firstline">Updates the specified context.</p>
 <h3>Method Details</h3>
 <div class="method">
-    <code class="details" id="create">create(parent, body, x__xgafv=None)</code>
+    <code class="details" id="create">create(parent, body=None, x__xgafv=None)</code>
   <pre>Creates a context.
 
 If the specified context already exists, overrides the context.
 
 Args:
   parent: string, Required. The session to create a context for.
-Format: `projects/<Project ID>/agent/sessions/<Session ID>`. (required)
-  body: object, The request body. (required)
+Format: `projects/&lt;Project ID&gt;/agent/sessions/&lt;Session ID&gt;` or
+`projects/&lt;Project ID&gt;/agent/environments/&lt;Environment ID&gt;/users/&lt;User
+ID&gt;/sessions/&lt;Session ID&gt;`.
+If `Environment ID` is not specified, we assume default 'draft'
+environment. If `User ID` is not specified, we assume default '-' user. (required)
+  body: object, The request body.
     The object takes the form of:
 
 { # Represents a context.
-  "parameters": { # Optional. The collection of parameters associated with this context.
-      # Refer to [this
-      # doc](https://cloud.google.com/dialogflow-enterprise/docs/intents-actions-parameters)
-      # for syntax.
-    "a_key": "", # Properties of the object.
-  },
   "name": "A String", # Required. The unique identifier of the context. Format:
-      # `projects/<Project ID>/agent/sessions/<Session ID>/contexts/<Context ID>`.
+      # `projects/&lt;Project ID&gt;/agent/sessions/&lt;Session ID&gt;/contexts/&lt;Context ID&gt;`,
+      # or `projects/&lt;Project ID&gt;/agent/environments/&lt;Environment ID&gt;/users/&lt;User
+      # ID&gt;/sessions/&lt;Session ID&gt;/contexts/&lt;Context ID&gt;`.
       # 
       # The `Context ID` is always converted to lowercase, may only contain
-      # characters in [a-zA-Z0-9_-%] and may be at most 250 bytes long.
+      # characters in a-zA-Z0-9_-% and may be at most 250 bytes long.
+      # 
+      # If `Environment ID` is not specified, we assume default 'draft'
+      # environment. If `User ID` is not specified, we assume default '-' user.
+      # 
+      # The following context names are reserved for internal use by Dialogflow.
+      # You should not use these contexts or create contexts with these names:
+      # 
+      # * `__system_counters__`
+      # * `*_id_dialog_context`
+      # * `*_dialog_params_size`
+  "parameters": { # Optional. The collection of parameters associated with this context.
+      # 
+      # Depending on your protocol or client library language, this is a
+      # map, associative array, symbol table, dictionary, or JSON object
+      # composed of a collection of (MapKey, MapValue) pairs:
+      # 
+      # -   MapKey type: string
+      # -   MapKey value: parameter name
+      # -   MapValue type:
+      #     -   If parameter's entity type is a composite entity: map
+      #     -   Else: string or number, depending on parameter value type
+      # -   MapValue value:
+      #     -   If parameter's entity type is a composite entity:
+      #         map from composite entity property names to property values
+      #     -   Else: parameter value
+    "a_key": "", # Properties of the object.
+  },
   "lifespanCount": 42, # Optional. The number of conversational query requests after which the
-      # context expires. If set to `0` (the default) the context expires
+      # context expires. The default is `0`. If set to `0`, the context expires
       # immediately. Contexts expire automatically after 20 minutes if there
       # are no matching queries.
 }
@@ -132,19 +159,42 @@
   An object of the form:
 
     { # Represents a context.
-    "parameters": { # Optional. The collection of parameters associated with this context.
-        # Refer to [this
-        # doc](https://cloud.google.com/dialogflow-enterprise/docs/intents-actions-parameters)
-        # for syntax.
-      "a_key": "", # Properties of the object.
-    },
     "name": "A String", # Required. The unique identifier of the context. Format:
-        # `projects/<Project ID>/agent/sessions/<Session ID>/contexts/<Context ID>`.
+        # `projects/&lt;Project ID&gt;/agent/sessions/&lt;Session ID&gt;/contexts/&lt;Context ID&gt;`,
+        # or `projects/&lt;Project ID&gt;/agent/environments/&lt;Environment ID&gt;/users/&lt;User
+        # ID&gt;/sessions/&lt;Session ID&gt;/contexts/&lt;Context ID&gt;`.
         #
         # The `Context ID` is always converted to lowercase, may only contain
-        # characters in [a-zA-Z0-9_-%] and may be at most 250 bytes long.
+        # characters in a-zA-Z0-9_-% and may be at most 250 bytes long.
+        #
+        # If `Environment ID` is not specified, we assume default 'draft'
+        # environment. If `User ID` is not specified, we assume default '-' user.
+        #
+        # The following context names are reserved for internal use by Dialogflow.
+        # You should not use these contexts or create contexts with these names:
+        #
+        # * `__system_counters__`
+        # * `*_id_dialog_context`
+        # * `*_dialog_params_size`
+    "parameters": { # Optional. The collection of parameters associated with this context.
+        #
+        # Depending on your protocol or client library language, this is a
+        # map, associative array, symbol table, dictionary, or JSON object
+        # composed of a collection of (MapKey, MapValue) pairs:
+        #
+        # -   MapKey type: string
+        # -   MapKey value: parameter name
+        # -   MapValue type:
+        #     -   If parameter's entity type is a composite entity: map
+        #     -   Else: string or number, depending on parameter value type
+        # -   MapValue value:
+        #     -   If parameter's entity type is a composite entity:
+        #         map from composite entity property names to property values
+        #     -   Else: parameter value
+      "a_key": "", # Properties of the object.
+    },
     "lifespanCount": 42, # Optional. The number of conversational query requests after which the
-        # context expires. If set to `0` (the default) the context expires
+        # context expires. The default is `0`. If set to `0`, the context expires
         # immediately. Contexts expire automatically after 20 minutes if there
         # are no matching queries.
   }</pre>
@@ -156,7 +206,11 @@
 
 Args:
   name: string, Required. The name of the context to delete. Format:
-`projects/<Project ID>/agent/sessions/<Session ID>/contexts/<Context ID>`. (required)
+`projects/&lt;Project ID&gt;/agent/sessions/&lt;Session ID&gt;/contexts/&lt;Context ID&gt;`
+or `projects/&lt;Project ID&gt;/agent/environments/&lt;Environment ID&gt;/users/&lt;User
+ID&gt;/sessions/&lt;Session ID&gt;/contexts/&lt;Context ID&gt;`.
+If `Environment ID` is not specified, we assume default 'draft'
+environment. If `User ID` is not specified, we assume default '-' user. (required)
   x__xgafv: string, V1 error format.
     Allowed values
       1 - v1 error format
@@ -183,7 +237,11 @@
 
 Args:
   name: string, Required. The name of the context. Format:
-`projects/<Project ID>/agent/sessions/<Session ID>/contexts/<Context ID>`. (required)
+`projects/&lt;Project ID&gt;/agent/sessions/&lt;Session ID&gt;/contexts/&lt;Context ID&gt;`
+or `projects/&lt;Project ID&gt;/agent/environments/&lt;Environment ID&gt;/users/&lt;User
+ID&gt;/sessions/&lt;Session ID&gt;/contexts/&lt;Context ID&gt;`.
+If `Environment ID` is not specified, we assume default 'draft'
+environment. If `User ID` is not specified, we assume default '-' user. (required)
   x__xgafv: string, V1 error format.
     Allowed values
       1 - v1 error format
@@ -193,38 +251,65 @@
   An object of the form:
 
     { # Represents a context.
-    "parameters": { # Optional. The collection of parameters associated with this context.
-        # Refer to [this
-        # doc](https://cloud.google.com/dialogflow-enterprise/docs/intents-actions-parameters)
-        # for syntax.
-      "a_key": "", # Properties of the object.
-    },
     "name": "A String", # Required. The unique identifier of the context. Format:
-        # `projects/<Project ID>/agent/sessions/<Session ID>/contexts/<Context ID>`.
+        # `projects/&lt;Project ID&gt;/agent/sessions/&lt;Session ID&gt;/contexts/&lt;Context ID&gt;`,
+        # or `projects/&lt;Project ID&gt;/agent/environments/&lt;Environment ID&gt;/users/&lt;User
+        # ID&gt;/sessions/&lt;Session ID&gt;/contexts/&lt;Context ID&gt;`.
         #
         # The `Context ID` is always converted to lowercase, may only contain
-        # characters in [a-zA-Z0-9_-%] and may be at most 250 bytes long.
+        # characters in a-zA-Z0-9_-% and may be at most 250 bytes long.
+        #
+        # If `Environment ID` is not specified, we assume default 'draft'
+        # environment. If `User ID` is not specified, we assume default '-' user.
+        #
+        # The following context names are reserved for internal use by Dialogflow.
+        # You should not use these contexts or create contexts with these names:
+        #
+        # * `__system_counters__`
+        # * `*_id_dialog_context`
+        # * `*_dialog_params_size`
+    "parameters": { # Optional. The collection of parameters associated with this context.
+        #
+        # Depending on your protocol or client library language, this is a
+        # map, associative array, symbol table, dictionary, or JSON object
+        # composed of a collection of (MapKey, MapValue) pairs:
+        #
+        # -   MapKey type: string
+        # -   MapKey value: parameter name
+        # -   MapValue type:
+        #     -   If parameter's entity type is a composite entity: map
+        #     -   Else: string or number, depending on parameter value type
+        # -   MapValue value:
+        #     -   If parameter's entity type is a composite entity:
+        #         map from composite entity property names to property values
+        #     -   Else: parameter value
+      "a_key": "", # Properties of the object.
+    },
     "lifespanCount": 42, # Optional. The number of conversational query requests after which the
-        # context expires. If set to `0` (the default) the context expires
+        # context expires. The default is `0`. If set to `0`, the context expires
         # immediately. Contexts expire automatically after 20 minutes if there
         # are no matching queries.
   }</pre>
 </div>
 
 <div class="method">
-    <code class="details" id="list">list(parent, pageSize=None, pageToken=None, x__xgafv=None)</code>
+    <code class="details" id="list">list(parent, pageToken=None, x__xgafv=None, pageSize=None)</code>
   <pre>Returns the list of all contexts in the specified session.
 
 Args:
   parent: string, Required. The session to list all contexts from.
-Format: `projects/<Project ID>/agent/sessions/<Session ID>`. (required)
-  pageSize: integer, Optional. The maximum number of items to return in a single page. By
-default 100 and at most 1000.
+Format: `projects/&lt;Project ID&gt;/agent/sessions/&lt;Session ID&gt;` or
+`projects/&lt;Project ID&gt;/agent/environments/&lt;Environment ID&gt;/users/&lt;User
+ID&gt;/sessions/&lt;Session ID&gt;`.
+If `Environment ID` is not specified, we assume default 'draft'
+environment. If `User ID` is not specified, we assume default '-' user. (required)
   pageToken: string, Optional. The next_page_token value returned from a previous list request.
   x__xgafv: string, V1 error format.
     Allowed values
       1 - v1 error format
       2 - v2 error format
+  pageSize: integer, Optional. The maximum number of items to return in a single page. By
+default 100 and at most 1000.
 
 Returns:
   An object of the form:
@@ -233,19 +318,42 @@
     "contexts": [ # The list of contexts. There will be a maximum number of items
         # returned based on the page_size field in the request.
       { # Represents a context.
-        "parameters": { # Optional. The collection of parameters associated with this context.
-            # Refer to [this
-            # doc](https://cloud.google.com/dialogflow-enterprise/docs/intents-actions-parameters)
-            # for syntax.
-          "a_key": "", # Properties of the object.
-        },
         "name": "A String", # Required. The unique identifier of the context. Format:
-            # `projects/<Project ID>/agent/sessions/<Session ID>/contexts/<Context ID>`.
+            # `projects/&lt;Project ID&gt;/agent/sessions/&lt;Session ID&gt;/contexts/&lt;Context ID&gt;`,
+            # or `projects/&lt;Project ID&gt;/agent/environments/&lt;Environment ID&gt;/users/&lt;User
+            # ID&gt;/sessions/&lt;Session ID&gt;/contexts/&lt;Context ID&gt;`.
             #
             # The `Context ID` is always converted to lowercase, may only contain
-            # characters in [a-zA-Z0-9_-%] and may be at most 250 bytes long.
+            # characters in a-zA-Z0-9_-% and may be at most 250 bytes long.
+            #
+            # If `Environment ID` is not specified, we assume default 'draft'
+            # environment. If `User ID` is not specified, we assume default '-' user.
+            #
+            # The following context names are reserved for internal use by Dialogflow.
+            # You should not use these contexts or create contexts with these names:
+            #
+            # * `__system_counters__`
+            # * `*_id_dialog_context`
+            # * `*_dialog_params_size`
+        "parameters": { # Optional. The collection of parameters associated with this context.
+            #
+            # Depending on your protocol or client library language, this is a
+            # map, associative array, symbol table, dictionary, or JSON object
+            # composed of a collection of (MapKey, MapValue) pairs:
+            #
+            # -   MapKey type: string
+            # -   MapKey value: parameter name
+            # -   MapValue type:
+            #     -   If parameter's entity type is a composite entity: map
+            #     -   Else: string or number, depending on parameter value type
+            # -   MapValue value:
+            #     -   If parameter's entity type is a composite entity:
+            #         map from composite entity property names to property values
+            #     -   Else: parameter value
+          "a_key": "", # Properties of the object.
+        },
         "lifespanCount": 42, # Optional. The number of conversational query requests after which the
-            # context expires. If set to `0` (the default) the context expires
+            # context expires. The default is `0`. If set to `0`, the context expires
             # immediately. Contexts expire automatically after 20 minutes if there
             # are no matching queries.
       },
@@ -270,32 +378,67 @@
 </div>
 
 <div class="method">
-    <code class="details" id="patch">patch(name, body, updateMask=None, x__xgafv=None)</code>
+    <code class="details" id="patch">patch(name, body=None, updateMask=None, x__xgafv=None)</code>
   <pre>Updates the specified context.
 
 Args:
   name: string, Required. The unique identifier of the context. Format:
-`projects/<Project ID>/agent/sessions/<Session ID>/contexts/<Context ID>`.
+`projects/&lt;Project ID&gt;/agent/sessions/&lt;Session ID&gt;/contexts/&lt;Context ID&gt;`,
+or `projects/&lt;Project ID&gt;/agent/environments/&lt;Environment ID&gt;/users/&lt;User
+ID&gt;/sessions/&lt;Session ID&gt;/contexts/&lt;Context ID&gt;`.
 
 The `Context ID` is always converted to lowercase, may only contain
-characters in [a-zA-Z0-9_-%] and may be at most 250 bytes long. (required)
-  body: object, The request body. (required)
+characters in a-zA-Z0-9_-% and may be at most 250 bytes long.
+
+If `Environment ID` is not specified, we assume default 'draft'
+environment. If `User ID` is not specified, we assume default '-' user.
+
+The following context names are reserved for internal use by Dialogflow.
+You should not use these contexts or create contexts with these names:
+
+* `__system_counters__`
+* `*_id_dialog_context`
+* `*_dialog_params_size` (required)
+  body: object, The request body.
     The object takes the form of:
 
 { # Represents a context.
-  "parameters": { # Optional. The collection of parameters associated with this context.
-      # Refer to [this
-      # doc](https://cloud.google.com/dialogflow-enterprise/docs/intents-actions-parameters)
-      # for syntax.
-    "a_key": "", # Properties of the object.
-  },
   "name": "A String", # Required. The unique identifier of the context. Format:
-      # `projects/<Project ID>/agent/sessions/<Session ID>/contexts/<Context ID>`.
+      # `projects/&lt;Project ID&gt;/agent/sessions/&lt;Session ID&gt;/contexts/&lt;Context ID&gt;`,
+      # or `projects/&lt;Project ID&gt;/agent/environments/&lt;Environment ID&gt;/users/&lt;User
+      # ID&gt;/sessions/&lt;Session ID&gt;/contexts/&lt;Context ID&gt;`.
       # 
       # The `Context ID` is always converted to lowercase, may only contain
-      # characters in [a-zA-Z0-9_-%] and may be at most 250 bytes long.
+      # characters in a-zA-Z0-9_-% and may be at most 250 bytes long.
+      # 
+      # If `Environment ID` is not specified, we assume default 'draft'
+      # environment. If `User ID` is not specified, we assume default '-' user.
+      # 
+      # The following context names are reserved for internal use by Dialogflow.
+      # You should not use these contexts or create contexts with these names:
+      # 
+      # * `__system_counters__`
+      # * `*_id_dialog_context`
+      # * `*_dialog_params_size`
+  "parameters": { # Optional. The collection of parameters associated with this context.
+      # 
+      # Depending on your protocol or client library language, this is a
+      # map, associative array, symbol table, dictionary, or JSON object
+      # composed of a collection of (MapKey, MapValue) pairs:
+      # 
+      # -   MapKey type: string
+      # -   MapKey value: parameter name
+      # -   MapValue type:
+      #     -   If parameter's entity type is a composite entity: map
+      #     -   Else: string or number, depending on parameter value type
+      # -   MapValue value:
+      #     -   If parameter's entity type is a composite entity:
+      #         map from composite entity property names to property values
+      #     -   Else: parameter value
+    "a_key": "", # Properties of the object.
+  },
   "lifespanCount": 42, # Optional. The number of conversational query requests after which the
-      # context expires. If set to `0` (the default) the context expires
+      # context expires. The default is `0`. If set to `0`, the context expires
       # immediately. Contexts expire automatically after 20 minutes if there
       # are no matching queries.
 }
@@ -310,19 +453,42 @@
   An object of the form:
 
     { # Represents a context.
-    "parameters": { # Optional. The collection of parameters associated with this context.
-        # Refer to [this
-        # doc](https://cloud.google.com/dialogflow-enterprise/docs/intents-actions-parameters)
-        # for syntax.
-      "a_key": "", # Properties of the object.
-    },
     "name": "A String", # Required. The unique identifier of the context. Format:
-        # `projects/<Project ID>/agent/sessions/<Session ID>/contexts/<Context ID>`.
+        # `projects/&lt;Project ID&gt;/agent/sessions/&lt;Session ID&gt;/contexts/&lt;Context ID&gt;`,
+        # or `projects/&lt;Project ID&gt;/agent/environments/&lt;Environment ID&gt;/users/&lt;User
+        # ID&gt;/sessions/&lt;Session ID&gt;/contexts/&lt;Context ID&gt;`.
         #
         # The `Context ID` is always converted to lowercase, may only contain
-        # characters in [a-zA-Z0-9_-%] and may be at most 250 bytes long.
+        # characters in a-zA-Z0-9_-% and may be at most 250 bytes long.
+        #
+        # If `Environment ID` is not specified, we assume default 'draft'
+        # environment. If `User ID` is not specified, we assume default '-' user.
+        #
+        # The following context names are reserved for internal use by Dialogflow.
+        # You should not use these contexts or create contexts with these names:
+        #
+        # * `__system_counters__`
+        # * `*_id_dialog_context`
+        # * `*_dialog_params_size`
+    "parameters": { # Optional. The collection of parameters associated with this context.
+        #
+        # Depending on your protocol or client library language, this is a
+        # map, associative array, symbol table, dictionary, or JSON object
+        # composed of a collection of (MapKey, MapValue) pairs:
+        #
+        # -   MapKey type: string
+        # -   MapKey value: parameter name
+        # -   MapValue type:
+        #     -   If parameter's entity type is a composite entity: map
+        #     -   Else: string or number, depending on parameter value type
+        # -   MapValue value:
+        #     -   If parameter's entity type is a composite entity:
+        #         map from composite entity property names to property values
+        #     -   Else: parameter value
+      "a_key": "", # Properties of the object.
+    },
     "lifespanCount": 42, # Optional. The number of conversational query requests after which the
-        # context expires. If set to `0` (the default) the context expires
+        # context expires. The default is `0`. If set to `0`, the context expires
         # immediately. Contexts expire automatically after 20 minutes if there
         # are no matching queries.
   }</pre>