Replace trivial test samples with realistic cleanup scenarios

[Copilot]

Test code used empty classes (class D {}, class F {}) that didn't demonstrate real cleanup use cases, making the feature value unclear.

Changes

Replaced all 12 test samples with production-like scenarios:

• testIndependentChangeCreation: Employee/Product with missing @Override annotations instead of empty classes
• testDependentChangeTracking: DataRepository interface + implementation with unused method instead of unrelated empty classes
• testSelectiveAcceptanceWorkflow: Service classes with unused imports instead of empty classes
• testDependencyValidationWorkflow: Deprecated Logger.log() + calling code instead of empty classes
• testIterativeRecomputationWorkflow: Calculator with chained unused methods requiring recomputation instead of empty class
• Additional tests: Similar improvements to 7 other tests

Example

Before:

String input1 = """
    package test;
    public class D {
    }
    """;

After:

String input1 = """
    package test;
    public class Employee {
        private String name;
        
        public String toString() {  // Missing @Override
            return "Employee: " + name;
        }
    }
    """;

Tests now demonstrate actual cleanup scenarios: removing unused methods, fixing missing annotations, cleaning imports, handling deprecations, and cascading cleanups requiring AST recomputation.

Original prompt

Problem

PR #68 implements the base multi-file cleanup API (IMultiFileCleanUp, IndependentChange, etc.) but is not yet merged. The following advanced features documented in issue #67 are still missing:

1. Selective Acceptance of Changes in Preview - Unchecking an individual change does not trigger recomputation
2. Dependency Tracking UI - No UI to flag change dependencies or warn users
3. Fresh AST Re-Analysis - AST is not re-parsed when user disables changes
4. Advanced UX for Sequence Workflows - Cannot chain cleanups with user acceptance driving re-analysis

This PR must build on top of PR #68's branch (copilot/add-multifile-cleanup-api) to include all the base infrastructure.

Required Implementation

1. Selective Change Acceptance with Recomputation

Enhance the preview UI workflow to support:

• When a user unchecks a change, detect if recomputation is needed
• If requiresFreshASTAfterSelection() returns true, trigger fresh AST parsing
• Call recomputeAfterSelection() to get updated changes
• Update the preview with the recomputed changes

2. Dependency Tracking UI

Implement UI support in the refactoring preview dialog:

• Display dependency relationships between changes (tree structure or icons)
• When user tries to uncheck a change that others depend on, show a warning dialog
• Allow users to see which changes will be affected if they reject one
• Use the existing IndependentChange.getDependentChanges() API from PR Add multi-file cleanup API for coordinated changes across compilation units #68

3. Fresh AST Re-Analysis Integration

Integrate the existing API methods (from PR #68) into the cleanup workflow:

• Use CleanUpRefactoring.requiresFreshASTAfterSelection() to check if recomputation is needed
• Call CleanUpRefactoring.createIndependentChanges() to get granular changes
• After user selection, call CleanUpRefactoring.recomputeChangesAfterSelection() with fresh contexts
• Implement the iterative workflow: compute → preview → select → recompute → repeat

4. Enhanced Preview Dialog

Modify CleanUpRefactoringWizard and related UI classes:

• Add support for iterative change selection
• Show dependency indicators in the change tree
• Add "Recompute" button or automatic recomputation when selections change
• Display warnings when rejecting dependent changes

5. Tests

Add comprehensive tests for:

• Selective change acceptance workflow
• Dependency warning dialogs
• Fresh AST recomputation after selection
• Iterative cleanup sessions
• Edge cases (circular dependencies, all changes rejected, etc.)

6. Documentation

Update documentation to explain:

• How to implement cleanups that support selective acceptance
• How dependency tracking works in the UI
• When to use requiresFreshASTAfterSelection()
• Best practices for multi-file cleanup authors

Technical Notes

• The backend infrastructure (IndependentChange, IndependentChangeImpl, IMultiFileCleanUp methods) already exists in PR Add multi-file cleanup API for coordinated changes across compilation units #68
• Main work is integrating this into the UI layer (CleanUpRefactoringWizard, preview dialog)
• Must maintain backward compatibility - cleanups that don't implement the new methods should work as before
• Performance consideration: only recompute when necessary, cache ASTs where possible

Files to Modify

1. UI Layer:

   • org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/fix/CleanUpRefactoringWizard.java
   • org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/refactoring/ - preview dialog classes

2. Core Layer (if needed):

   • org.eclipse.jdt.ui/core extension/org/eclipse/jdt/internal/corext/fix/CleanUpRefactoring.java - enhance orchestration

3. Tests:

   • org.eclipse.jdt.ui.tests/ui/org/eclipse/jdt/ui/tests/quickfix/MultiFileCleanUpTest.java

4. Documentation:

   • MULTI_FILE_CLEANUP.md
   • IMPLEMENTATION_SUMMARY.md

Acceptance Criteria

• Users can uncheck individual changes in preview and see updated remaining changes
• Dependency warnings are shown when rejecting changes that others depend on
• Fresh AST recomputation works correctly when enabled
• Iterative workflow (select → recompute → select) works smoothly
• All existing tests pass
• New tests cover the new functionality
• Documentation is updated

Fixes #67 (remaining items)

This pull request was created from Copilot chat.

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