# No ThreadGroup Usage
# Detects usage of ThreadGroup which is deprecated/unsafe
id: no-threadgroup
name: ThreadGroup Should Not Be Used
severity: warning
category: reliability
defect_class: correctness
inline_tier: blocking
language: java

message: "ThreadGroup should not be used — it's obsolete and unsafe"

description: |
  ThreadGroup is obsolete and has security vulnerabilities.
  Use ExecutorService and ThreadPoolExecutor instead for better
  thread management and security.

  ✅ FIX: Use ExecutorService instead

  ```java
  ExecutorService executor = Executors.newFixedThreadPool(10);
  executor.submit(task);
  ```

query: |
  (object_creation_expression
    type: (type_identifier) @TYPE (#eq? @TYPE "ThreadGroup"))
  (local_variable_declaration
    type: (type_identifier) @TYPE (#eq? @TYPE "ThreadGroup"))
  (formal_parameter
    type: (type_identifier) @TYPE (#eq? @TYPE "ThreadGroup"))

metavars:
  - TYPE

tags:
  - reliability
  - java
  - concurrency
  - deprecated
  - cert

examples:
  bad: |
    ThreadGroup group = new ThreadGroup("workers");  // BAD
    Thread t = new Thread(group, runnable);

  good: |
    ExecutorService executor = Executors.newFixedThreadPool(4);  // GOOD
    executor.submit(runnable);

has_fix: false