Release v1.6.0 (#324)

* Update version and changelog for v1.6.0
* Update docs
diff --git a/docs/dyn/compute_beta.backendServices.html b/docs/dyn/compute_beta.backendServices.html
index 43e35c1..7132a80 100644
--- a/docs/dyn/compute_beta.backendServices.html
+++ b/docs/dyn/compute_beta.backendServices.html
@@ -170,6 +170,7 @@
               "affinityCookieTtlSec": 42, # Lifetime of cookies in seconds if session_affinity is GENERATED_COOKIE. If set to 0, the cookie is non-persistent and lasts only until the end of the browser session (or equivalent). The maximum allowed value for TTL is one day.
                   #
                   # When the load balancing scheme is INTERNAL, this field is not used.
+              "id": "A String", # [Output Only] The unique identifier for the resource. This identifier is defined by the server.
               "port": 42, # Deprecated in favor of portName. The TCP port to connect on the backend. The default value is 80.
                   #
                   # This cannot be used for internal load balancing.
@@ -221,7 +222,12 @@
                   #
                   # When the protocol is UDP, this field is not used.
               "creationTimestamp": "A String", # [Output Only] Creation timestamp in RFC3339 text format.
-              "id": "A String", # [Output Only] The unique identifier for the resource. This identifier is defined by the server.
+              "iap": { # Identity-Aware Proxy (Cloud Gatekeeper)
+                "oauth2ClientId": "A String",
+                "enabled": True or False,
+                "oauth2ClientSecret": "A String",
+                "oauth2ClientSecretSha256": "A String",
+              },
               "selfLink": "A String", # [Output Only] Server-defined URL for the resource.
               "name": "A String", # Name of the resource. Provided by the client when the resource is created. The name must be 1-63 characters long, and comply with RFC1035. Specifically, the name must be 1-63 characters long and match the regular expression [a-z]([-a-z0-9]*[a-z0-9])? which means the first character must be a lowercase letter, and all following characters must be a dash, lowercase letter, or digit, except the last character, which cannot be a dash.
             },
@@ -302,7 +308,7 @@
     },
     "endTime": "A String", # [Output Only] The time that this operation was completed. This value is in RFC3339 text format.
     "selfLink": "A String", # [Output Only] Server-defined URL for the resource.
-    "targetLink": "A String", # [Output Only] The URL of the resource that the operation modifies. If creating a persistent disk snapshot, this points to the persistent disk that the snapshot was created from.
+    "targetLink": "A String", # [Output Only] The URL of the resource that the operation modifies. For operations related to creating a snapshot, this points to the persistent disk that the snapshot was created from.
   }</pre>
 </div>
 
@@ -337,6 +343,7 @@
       "affinityCookieTtlSec": 42, # Lifetime of cookies in seconds if session_affinity is GENERATED_COOKIE. If set to 0, the cookie is non-persistent and lasts only until the end of the browser session (or equivalent). The maximum allowed value for TTL is one day.
           #
           # When the load balancing scheme is INTERNAL, this field is not used.
+      "id": "A String", # [Output Only] The unique identifier for the resource. This identifier is defined by the server.
       "port": 42, # Deprecated in favor of portName. The TCP port to connect on the backend. The default value is 80.
           #
           # This cannot be used for internal load balancing.
@@ -388,7 +395,12 @@
           #
           # When the protocol is UDP, this field is not used.
       "creationTimestamp": "A String", # [Output Only] Creation timestamp in RFC3339 text format.
-      "id": "A String", # [Output Only] The unique identifier for the resource. This identifier is defined by the server.
+      "iap": { # Identity-Aware Proxy (Cloud Gatekeeper)
+        "oauth2ClientId": "A String",
+        "enabled": True or False,
+        "oauth2ClientSecret": "A String",
+        "oauth2ClientSecretSha256": "A String",
+      },
       "selfLink": "A String", # [Output Only] Server-defined URL for the resource.
       "name": "A String", # Name of the resource. Provided by the client when the resource is created. The name must be 1-63 characters long, and comply with RFC1035. Specifically, the name must be 1-63 characters long and match the regular expression [a-z]([-a-z0-9]*[a-z0-9])? which means the first character must be a lowercase letter, and all following characters must be a dash, lowercase letter, or digit, except the last character, which cannot be a dash.
     }</pre>
@@ -454,6 +466,7 @@
     "affinityCookieTtlSec": 42, # Lifetime of cookies in seconds if session_affinity is GENERATED_COOKIE. If set to 0, the cookie is non-persistent and lasts only until the end of the browser session (or equivalent). The maximum allowed value for TTL is one day.
         # 
         # When the load balancing scheme is INTERNAL, this field is not used.
+    "id": "A String", # [Output Only] The unique identifier for the resource. This identifier is defined by the server.
     "port": 42, # Deprecated in favor of portName. The TCP port to connect on the backend. The default value is 80.
         # 
         # This cannot be used for internal load balancing.
@@ -505,7 +518,12 @@
         # 
         # When the protocol is UDP, this field is not used.
     "creationTimestamp": "A String", # [Output Only] Creation timestamp in RFC3339 text format.
-    "id": "A String", # [Output Only] The unique identifier for the resource. This identifier is defined by the server.
+    "iap": { # Identity-Aware Proxy (Cloud Gatekeeper)
+      "oauth2ClientId": "A String",
+      "enabled": True or False,
+      "oauth2ClientSecret": "A String",
+      "oauth2ClientSecretSha256": "A String",
+    },
     "selfLink": "A String", # [Output Only] Server-defined URL for the resource.
     "name": "A String", # Name of the resource. Provided by the client when the resource is created. The name must be 1-63 characters long, and comply with RFC1035. Specifically, the name must be 1-63 characters long and match the regular expression [a-z]([-a-z0-9]*[a-z0-9])? which means the first character must be a lowercase letter, and all following characters must be a dash, lowercase letter, or digit, except the last character, which cannot be a dash.
   }
@@ -557,7 +575,7 @@
     },
     "endTime": "A String", # [Output Only] The time that this operation was completed. This value is in RFC3339 text format.
     "selfLink": "A String", # [Output Only] Server-defined URL for the resource.
-    "targetLink": "A String", # [Output Only] The URL of the resource that the operation modifies. If creating a persistent disk snapshot, this points to the persistent disk that the snapshot was created from.
+    "targetLink": "A String", # [Output Only] The URL of the resource that the operation modifies. For operations related to creating a snapshot, this points to the persistent disk that the snapshot was created from.
   }</pre>
 </div>
 
@@ -610,6 +628,7 @@
           "affinityCookieTtlSec": 42, # Lifetime of cookies in seconds if session_affinity is GENERATED_COOKIE. If set to 0, the cookie is non-persistent and lasts only until the end of the browser session (or equivalent). The maximum allowed value for TTL is one day.
               #
               # When the load balancing scheme is INTERNAL, this field is not used.
+          "id": "A String", # [Output Only] The unique identifier for the resource. This identifier is defined by the server.
           "port": 42, # Deprecated in favor of portName. The TCP port to connect on the backend. The default value is 80.
               #
               # This cannot be used for internal load balancing.
@@ -661,7 +680,12 @@
               #
               # When the protocol is UDP, this field is not used.
           "creationTimestamp": "A String", # [Output Only] Creation timestamp in RFC3339 text format.
-          "id": "A String", # [Output Only] The unique identifier for the resource. This identifier is defined by the server.
+          "iap": { # Identity-Aware Proxy (Cloud Gatekeeper)
+            "oauth2ClientId": "A String",
+            "enabled": True or False,
+            "oauth2ClientSecret": "A String",
+            "oauth2ClientSecretSha256": "A String",
+          },
           "selfLink": "A String", # [Output Only] Server-defined URL for the resource.
           "name": "A String", # Name of the resource. Provided by the client when the resource is created. The name must be 1-63 characters long, and comply with RFC1035. Specifically, the name must be 1-63 characters long and match the regular expression [a-z]([-a-z0-9]*[a-z0-9])? which means the first character must be a lowercase letter, and all following characters must be a dash, lowercase letter, or digit, except the last character, which cannot be a dash.
         },
@@ -716,6 +740,7 @@
     "affinityCookieTtlSec": 42, # Lifetime of cookies in seconds if session_affinity is GENERATED_COOKIE. If set to 0, the cookie is non-persistent and lasts only until the end of the browser session (or equivalent). The maximum allowed value for TTL is one day.
         # 
         # When the load balancing scheme is INTERNAL, this field is not used.
+    "id": "A String", # [Output Only] The unique identifier for the resource. This identifier is defined by the server.
     "port": 42, # Deprecated in favor of portName. The TCP port to connect on the backend. The default value is 80.
         # 
         # This cannot be used for internal load balancing.
@@ -767,7 +792,12 @@
         # 
         # When the protocol is UDP, this field is not used.
     "creationTimestamp": "A String", # [Output Only] Creation timestamp in RFC3339 text format.
-    "id": "A String", # [Output Only] The unique identifier for the resource. This identifier is defined by the server.
+    "iap": { # Identity-Aware Proxy (Cloud Gatekeeper)
+      "oauth2ClientId": "A String",
+      "enabled": True or False,
+      "oauth2ClientSecret": "A String",
+      "oauth2ClientSecretSha256": "A String",
+    },
     "selfLink": "A String", # [Output Only] Server-defined URL for the resource.
     "name": "A String", # Name of the resource. Provided by the client when the resource is created. The name must be 1-63 characters long, and comply with RFC1035. Specifically, the name must be 1-63 characters long and match the regular expression [a-z]([-a-z0-9]*[a-z0-9])? which means the first character must be a lowercase letter, and all following characters must be a dash, lowercase letter, or digit, except the last character, which cannot be a dash.
   }
@@ -819,7 +849,7 @@
     },
     "endTime": "A String", # [Output Only] The time that this operation was completed. This value is in RFC3339 text format.
     "selfLink": "A String", # [Output Only] Server-defined URL for the resource.
-    "targetLink": "A String", # [Output Only] The URL of the resource that the operation modifies. If creating a persistent disk snapshot, this points to the persistent disk that the snapshot was created from.
+    "targetLink": "A String", # [Output Only] The URL of the resource that the operation modifies. For operations related to creating a snapshot, this points to the persistent disk that the snapshot was created from.
   }</pre>
 </div>
 
@@ -880,6 +910,7 @@
     "affinityCookieTtlSec": 42, # Lifetime of cookies in seconds if session_affinity is GENERATED_COOKIE. If set to 0, the cookie is non-persistent and lasts only until the end of the browser session (or equivalent). The maximum allowed value for TTL is one day.
         # 
         # When the load balancing scheme is INTERNAL, this field is not used.
+    "id": "A String", # [Output Only] The unique identifier for the resource. This identifier is defined by the server.
     "port": 42, # Deprecated in favor of portName. The TCP port to connect on the backend. The default value is 80.
         # 
         # This cannot be used for internal load balancing.
@@ -931,7 +962,12 @@
         # 
         # When the protocol is UDP, this field is not used.
     "creationTimestamp": "A String", # [Output Only] Creation timestamp in RFC3339 text format.
-    "id": "A String", # [Output Only] The unique identifier for the resource. This identifier is defined by the server.
+    "iap": { # Identity-Aware Proxy (Cloud Gatekeeper)
+      "oauth2ClientId": "A String",
+      "enabled": True or False,
+      "oauth2ClientSecret": "A String",
+      "oauth2ClientSecretSha256": "A String",
+    },
     "selfLink": "A String", # [Output Only] Server-defined URL for the resource.
     "name": "A String", # Name of the resource. Provided by the client when the resource is created. The name must be 1-63 characters long, and comply with RFC1035. Specifically, the name must be 1-63 characters long and match the regular expression [a-z]([-a-z0-9]*[a-z0-9])? which means the first character must be a lowercase letter, and all following characters must be a dash, lowercase letter, or digit, except the last character, which cannot be a dash.
   }
@@ -983,7 +1019,7 @@
     },
     "endTime": "A String", # [Output Only] The time that this operation was completed. This value is in RFC3339 text format.
     "selfLink": "A String", # [Output Only] Server-defined URL for the resource.
-    "targetLink": "A String", # [Output Only] The URL of the resource that the operation modifies. If creating a persistent disk snapshot, this points to the persistent disk that the snapshot was created from.
+    "targetLink": "A String", # [Output Only] The URL of the resource that the operation modifies. For operations related to creating a snapshot, this points to the persistent disk that the snapshot was created from.
   }</pre>
 </div>