chore: Update discovery artifacts (#1410)

## Deleted keys were detected in the following stable discovery artifacts:
managedidentities v1 https://github.com/googleapis/google-api-python-client/commit/e96adbb1ba3e4e56d916cc28474f85543f17ad0e

## Discovery Artifact Change Summary:
feat(appengine): update the api https://github.com/googleapis/google-api-python-client/commit/ffcf86035a751e98a763c8a2d54b70d3a55ca14d
feat(containeranalysis): update the api https://github.com/googleapis/google-api-python-client/commit/9a1c70b7df3e074fc9fbd0eebdaf75a91046078c
feat(documentai): update the api https://github.com/googleapis/google-api-python-client/commit/07a6e774ac185442a99437896eaee774946b5846
feat(drive): update the api https://github.com/googleapis/google-api-python-client/commit/773910fdf25b084aa3623d24fe99c8a1330fbecb
feat(managedidentities): update the api https://github.com/googleapis/google-api-python-client/commit/e96adbb1ba3e4e56d916cc28474f85543f17ad0e
feat(spanner): update the api https://github.com/googleapis/google-api-python-client/commit/87da2f3605ec1b8986324cddc33f2b5601d3e896
diff --git a/docs/dyn/spanner_v1.projects.instances.databases.sessions.html b/docs/dyn/spanner_v1.projects.instances.databases.sessions.html
index e7920eb..1cbdde8 100644
--- a/docs/dyn/spanner_v1.projects.instances.databases.sessions.html
+++ b/docs/dyn/spanner_v1.projects.instances.databases.sessions.html
@@ -421,7 +421,14 @@
         "a_key": { # `Type` indicates the type of a Cloud Spanner value, as might be stored in a table cell or returned from an SQL query.
           "arrayElementType": # Object with schema name: Type # If code == ARRAY, then `array_element_type` is the type of the array elements.
           "code": "A String", # Required. The TypeCode for this type.
-          "structType": # Object with schema name: StructType # If code == STRUCT, then `struct_type` provides type information for the struct's fields.
+          "structType": { # `StructType` defines the fields of a STRUCT type. # If code == STRUCT, then `struct_type` provides type information for the struct's fields.
+            "fields": [ # The list of fields that make up this struct. Order is significant, because values of this struct type are represented as lists, where the order of field values matches the order of fields in the StructType. In turn, the order of fields matches the order of columns in a read request, or the order of fields in the `SELECT` clause of a query.
+              { # Message representing a single field of a struct.
+                "name": "A String", # The name of the field. For reads, this is the column name. For SQL queries, it is the column alias (e.g., `"Word"` in the query `"SELECT 'hello' AS Word"`), or the column name (e.g., `"ColName"` in the query `"SELECT ColName FROM Table"`). Some columns might have an empty name (e.g., `"SELECT UPPER(ColName)"`). Note that a query result can contain multiple fields with the same name.
+                "type": # Object with schema name: Type # The type of the field.
+              },
+            ],
+          },
         },
       },
       "params": { # Parameter names and values that bind to placeholders in the DML string. A parameter placeholder consists of the `@` character followed by the parameter name (for example, `@firstName`). Parameter names can contain letters, numbers, and underscores. Parameters can appear anywhere that a literal value is expected. The same parameter name can be used more than once, for example: `"WHERE id > @msg_id AND id < @msg_id + 100"` It is an error to execute a SQL statement with unbound parameters.
@@ -479,11 +486,7 @@
           "fields": [ # The list of fields that make up this struct. Order is significant, because values of this struct type are represented as lists, where the order of field values matches the order of fields in the StructType. In turn, the order of fields matches the order of columns in a read request, or the order of fields in the `SELECT` clause of a query.
             { # Message representing a single field of a struct.
               "name": "A String", # The name of the field. For reads, this is the column name. For SQL queries, it is the column alias (e.g., `"Word"` in the query `"SELECT 'hello' AS Word"`), or the column name (e.g., `"ColName"` in the query `"SELECT ColName FROM Table"`). Some columns might have an empty name (e.g., `"SELECT UPPER(ColName)"`). Note that a query result can contain multiple fields with the same name.
-              "type": { # `Type` indicates the type of a Cloud Spanner value, as might be stored in a table cell or returned from an SQL query. # The type of the field.
-                "arrayElementType": # Object with schema name: Type # If code == ARRAY, then `array_element_type` is the type of the array elements.
-                "code": "A String", # Required. The TypeCode for this type.
-                "structType": # Object with schema name: StructType # If code == STRUCT, then `struct_type` provides type information for the struct's fields.
-              },
+              "type": # Object with schema name: Type # The type of the field.
             },
           ],
         },
@@ -560,7 +563,14 @@
     "a_key": { # `Type` indicates the type of a Cloud Spanner value, as might be stored in a table cell or returned from an SQL query.
       "arrayElementType": # Object with schema name: Type # If code == ARRAY, then `array_element_type` is the type of the array elements.
       "code": "A String", # Required. The TypeCode for this type.
-      "structType": # Object with schema name: StructType # If code == STRUCT, then `struct_type` provides type information for the struct's fields.
+      "structType": { # `StructType` defines the fields of a STRUCT type. # If code == STRUCT, then `struct_type` provides type information for the struct's fields.
+        "fields": [ # The list of fields that make up this struct. Order is significant, because values of this struct type are represented as lists, where the order of field values matches the order of fields in the StructType. In turn, the order of fields matches the order of columns in a read request, or the order of fields in the `SELECT` clause of a query.
+          { # Message representing a single field of a struct.
+            "name": "A String", # The name of the field. For reads, this is the column name. For SQL queries, it is the column alias (e.g., `"Word"` in the query `"SELECT 'hello' AS Word"`), or the column name (e.g., `"ColName"` in the query `"SELECT ColName FROM Table"`). Some columns might have an empty name (e.g., `"SELECT UPPER(ColName)"`). Note that a query result can contain multiple fields with the same name.
+            "type": # Object with schema name: Type # The type of the field.
+          },
+        ],
+      },
     },
   },
   "params": { # Parameter names and values that bind to placeholders in the SQL string. A parameter placeholder consists of the `@` character followed by the parameter name (for example, `@firstName`). Parameter names must conform to the naming requirements of identifiers as specified at https://cloud.google.com/spanner/docs/lexical#identifiers. Parameters can appear anywhere that a literal value is expected. The same parameter name can be used more than once, for example: `"WHERE id > @msg_id AND id < @msg_id + 100"` It is an error to execute a SQL statement with unbound parameters.
@@ -627,11 +637,7 @@
       "fields": [ # The list of fields that make up this struct. Order is significant, because values of this struct type are represented as lists, where the order of field values matches the order of fields in the StructType. In turn, the order of fields matches the order of columns in a read request, or the order of fields in the `SELECT` clause of a query.
         { # Message representing a single field of a struct.
           "name": "A String", # The name of the field. For reads, this is the column name. For SQL queries, it is the column alias (e.g., `"Word"` in the query `"SELECT 'hello' AS Word"`), or the column name (e.g., `"ColName"` in the query `"SELECT ColName FROM Table"`). Some columns might have an empty name (e.g., `"SELECT UPPER(ColName)"`). Note that a query result can contain multiple fields with the same name.
-          "type": { # `Type` indicates the type of a Cloud Spanner value, as might be stored in a table cell or returned from an SQL query. # The type of the field.
-            "arrayElementType": # Object with schema name: Type # If code == ARRAY, then `array_element_type` is the type of the array elements.
-            "code": "A String", # Required. The TypeCode for this type.
-            "structType": # Object with schema name: StructType # If code == STRUCT, then `struct_type` provides type information for the struct's fields.
-          },
+          "type": # Object with schema name: Type # The type of the field.
         },
       ],
     },
@@ -697,7 +703,14 @@
     "a_key": { # `Type` indicates the type of a Cloud Spanner value, as might be stored in a table cell or returned from an SQL query.
       "arrayElementType": # Object with schema name: Type # If code == ARRAY, then `array_element_type` is the type of the array elements.
       "code": "A String", # Required. The TypeCode for this type.
-      "structType": # Object with schema name: StructType # If code == STRUCT, then `struct_type` provides type information for the struct's fields.
+      "structType": { # `StructType` defines the fields of a STRUCT type. # If code == STRUCT, then `struct_type` provides type information for the struct's fields.
+        "fields": [ # The list of fields that make up this struct. Order is significant, because values of this struct type are represented as lists, where the order of field values matches the order of fields in the StructType. In turn, the order of fields matches the order of columns in a read request, or the order of fields in the `SELECT` clause of a query.
+          { # Message representing a single field of a struct.
+            "name": "A String", # The name of the field. For reads, this is the column name. For SQL queries, it is the column alias (e.g., `"Word"` in the query `"SELECT 'hello' AS Word"`), or the column name (e.g., `"ColName"` in the query `"SELECT ColName FROM Table"`). Some columns might have an empty name (e.g., `"SELECT UPPER(ColName)"`). Note that a query result can contain multiple fields with the same name.
+            "type": # Object with schema name: Type # The type of the field.
+          },
+        ],
+      },
     },
   },
   "params": { # Parameter names and values that bind to placeholders in the SQL string. A parameter placeholder consists of the `@` character followed by the parameter name (for example, `@firstName`). Parameter names must conform to the naming requirements of identifiers as specified at https://cloud.google.com/spanner/docs/lexical#identifiers. Parameters can appear anywhere that a literal value is expected. The same parameter name can be used more than once, for example: `"WHERE id > @msg_id AND id < @msg_id + 100"` It is an error to execute a SQL statement with unbound parameters.
@@ -765,11 +778,7 @@
       "fields": [ # The list of fields that make up this struct. Order is significant, because values of this struct type are represented as lists, where the order of field values matches the order of fields in the StructType. In turn, the order of fields matches the order of columns in a read request, or the order of fields in the `SELECT` clause of a query.
         { # Message representing a single field of a struct.
           "name": "A String", # The name of the field. For reads, this is the column name. For SQL queries, it is the column alias (e.g., `"Word"` in the query `"SELECT 'hello' AS Word"`), or the column name (e.g., `"ColName"` in the query `"SELECT ColName FROM Table"`). Some columns might have an empty name (e.g., `"SELECT UPPER(ColName)"`). Note that a query result can contain multiple fields with the same name.
-          "type": { # `Type` indicates the type of a Cloud Spanner value, as might be stored in a table cell or returned from an SQL query. # The type of the field.
-            "arrayElementType": # Object with schema name: Type # If code == ARRAY, then `array_element_type` is the type of the array elements.
-            "code": "A String", # Required. The TypeCode for this type.
-            "structType": # Object with schema name: StructType # If code == STRUCT, then `struct_type` provides type information for the struct's fields.
-          },
+          "type": # Object with schema name: Type # The type of the field.
         },
       ],
     },
@@ -904,7 +913,14 @@
     "a_key": { # `Type` indicates the type of a Cloud Spanner value, as might be stored in a table cell or returned from an SQL query.
       "arrayElementType": # Object with schema name: Type # If code == ARRAY, then `array_element_type` is the type of the array elements.
       "code": "A String", # Required. The TypeCode for this type.
-      "structType": # Object with schema name: StructType # If code == STRUCT, then `struct_type` provides type information for the struct's fields.
+      "structType": { # `StructType` defines the fields of a STRUCT type. # If code == STRUCT, then `struct_type` provides type information for the struct's fields.
+        "fields": [ # The list of fields that make up this struct. Order is significant, because values of this struct type are represented as lists, where the order of field values matches the order of fields in the StructType. In turn, the order of fields matches the order of columns in a read request, or the order of fields in the `SELECT` clause of a query.
+          { # Message representing a single field of a struct.
+            "name": "A String", # The name of the field. For reads, this is the column name. For SQL queries, it is the column alias (e.g., `"Word"` in the query `"SELECT 'hello' AS Word"`), or the column name (e.g., `"ColName"` in the query `"SELECT ColName FROM Table"`). Some columns might have an empty name (e.g., `"SELECT UPPER(ColName)"`). Note that a query result can contain multiple fields with the same name.
+            "type": # Object with schema name: Type # The type of the field.
+          },
+        ],
+      },
     },
   },
   "params": { # Parameter names and values that bind to placeholders in the SQL string. A parameter placeholder consists of the `@` character followed by the parameter name (for example, `@firstName`). Parameter names can contain letters, numbers, and underscores. Parameters can appear anywhere that a literal value is expected. The same parameter name can be used more than once, for example: `"WHERE id > @msg_id AND id < @msg_id + 100"` It is an error to execute a SQL statement with unbound parameters.
@@ -1160,11 +1176,7 @@
       "fields": [ # The list of fields that make up this struct. Order is significant, because values of this struct type are represented as lists, where the order of field values matches the order of fields in the StructType. In turn, the order of fields matches the order of columns in a read request, or the order of fields in the `SELECT` clause of a query.
         { # Message representing a single field of a struct.
           "name": "A String", # The name of the field. For reads, this is the column name. For SQL queries, it is the column alias (e.g., `"Word"` in the query `"SELECT 'hello' AS Word"`), or the column name (e.g., `"ColName"` in the query `"SELECT ColName FROM Table"`). Some columns might have an empty name (e.g., `"SELECT UPPER(ColName)"`). Note that a query result can contain multiple fields with the same name.
-          "type": { # `Type` indicates the type of a Cloud Spanner value, as might be stored in a table cell or returned from an SQL query. # The type of the field.
-            "arrayElementType": # Object with schema name: Type # If code == ARRAY, then `array_element_type` is the type of the array elements.
-            "code": "A String", # Required. The TypeCode for this type.
-            "structType": # Object with schema name: StructType # If code == STRUCT, then `struct_type` provides type information for the struct's fields.
-          },
+          "type": # Object with schema name: Type # The type of the field.
         },
       ],
     },
@@ -1336,11 +1348,7 @@
       "fields": [ # The list of fields that make up this struct. Order is significant, because values of this struct type are represented as lists, where the order of field values matches the order of fields in the StructType. In turn, the order of fields matches the order of columns in a read request, or the order of fields in the `SELECT` clause of a query.
         { # Message representing a single field of a struct.
           "name": "A String", # The name of the field. For reads, this is the column name. For SQL queries, it is the column alias (e.g., `"Word"` in the query `"SELECT 'hello' AS Word"`), or the column name (e.g., `"ColName"` in the query `"SELECT ColName FROM Table"`). Some columns might have an empty name (e.g., `"SELECT UPPER(ColName)"`). Note that a query result can contain multiple fields with the same name.
-          "type": { # `Type` indicates the type of a Cloud Spanner value, as might be stored in a table cell or returned from an SQL query. # The type of the field.
-            "arrayElementType": # Object with schema name: Type # If code == ARRAY, then `array_element_type` is the type of the array elements.
-            "code": "A String", # Required. The TypeCode for this type.
-            "structType": # Object with schema name: StructType # If code == STRUCT, then `struct_type` provides type information for the struct's fields.
-          },
+          "type": # Object with schema name: Type # The type of the field.
         },
       ],
     },