feat: adding ThinkingConfig to v1 client library

PiperOrigin-RevId: 751263476

Author: Google APIs

google/cloud/aiplatform/v1/content.proto

@@ -211,6 +211,13 @@ message GenerationConfig {
     }
   }
 
+  // Config for thinking features.
+  message ThinkingConfig {
+    // Optional. Indicates the thinking budget in tokens.
+    // This is only applied when enable_thinking is true.
+    optional int32 thinking_budget = 3 [(google.api.field_behavior) = OPTIONAL];
+  }
+
   // Optional. Controls the randomness of predictions.
   optional float temperature = 1 [(google.api.field_behavior) = OPTIONAL];
 
@@ -265,6 +272,11 @@ message GenerationConfig {
   // Optional. Routing configuration.
   optional RoutingConfig routing_config = 17
       [(google.api.field_behavior) = OPTIONAL];
+
+  // Optional. Config for thinking features.
+  // An error will be returned if this field is set for models that don't
+  // support thinking.
+  ThinkingConfig thinking_config = 25 [(google.api.field_behavior) = OPTIONAL];
 }
 
 // Safety settings.