Extracting local variables and refactoring leads to naming conflicts

[provide a description of the issue]

Environment

Operating System: Windows11
JDK version: 17
Visual Studio Code version: 1.88
Java extension version: 1.29

Steps To Reproduce

1. select "20"
2. click “Refacator-Extract local variable”
3. new variable name " existingVariable"

public class OriginalClass {
public void method() {
int existingVariable = 10;
// extract variable "20" , name :"existingVariable"
System.out.println(20);
}
}

refactoring result:

Reason: When extracting local variables, there was no detection of naming conflicts between the new variable name and the context

Expected behavior: Check for naming conflicts before and after refactoring, and provide warning prompts

Reproduce the reported Extract local variable refactoring in VS Code with the Java and extension versions listed, using the provided OriginalClass example and an existingVariable name. Trace the refactoring entry point to determine where conflicts are checked. Done means the conflict is detected before or after refactoring and a warning is shown instead of silently producing the conflicting result.