Program: 12125
Project: 12125
Buggy source:
private void modifyTargetPublicFieldInstructions(MethodDeclaration newMethodDeclaration){
  ExpressionExtractor extractor=new ExpressionExtractor();
  List<Expression> sourceFieldInstructions=extractor.getVariableInstructions(sourceMethod.getBody());
  List<Expression> newFieldInstructions=extractor.getVariableInstructions(newMethodDeclaration.getBody());
  FieldDeclaration[] fields=targetTypeDeclaration.getFields();
  for (  FieldDeclaration field : fields) {
    List<VariableDeclarationFragment> fragments=field.fragments();
    for (    VariableDeclarationFragment fragment : fragments) {
      SimpleName fragmentName=fragment.getName();
      int i=0;
      for (      Expression expression : sourceFieldInstructions) {
        SimpleName simpleName=(SimpleName)expression;
        if (simpleName.getParent() instanceof QualifiedName && fragmentName.getIdentifier().equals(simpleName.getIdentifier())) {
          QualifiedName qualifiedName=(QualifiedName)simpleName.getParent();
          if ((qualifiedName.getQualifier().resolveTypeBinding().isEqualTo(targetTypeDeclaration.resolveBinding()) || targetTypeDeclaration.resolveBinding().isEqualTo(qualifiedName.getQualifier().resolveTypeBinding().getSuperclass())) && qualifiedName.getQualifier().getFullyQualifiedName().equals(targetClassVariableName)) {
            SimpleName newSimpleName=(SimpleName)newFieldInstructions.get(i);
            targetRewriter.replace(newSimpleName.getParent(),simpleName,null);
          }
        }
 else         if (simpleName.getParent() instanceof FieldAccess && fragmentName.getIdentifier().equals(simpleName.getIdentifier())) {
          FieldAccess fieldAccess=(FieldAccess)simpleName.getParent();
          Expression fieldAccessExpression=fieldAccess.getExpression();
          if (fieldAccessExpression instanceof FieldAccess) {
            FieldAccess invokerFieldAccess=(FieldAccess)fieldAccessExpression;
            if ((invokerFieldAccess.resolveTypeBinding().isEqualTo(targetTypeDeclaration.resolveBinding()) || targetTypeDeclaration.resolveBinding().isEqualTo(invokerFieldAccess.resolveTypeBinding().getSuperclass())) && invokerFieldAccess.getName().getIdentifier().equals(targetClassVariableName) && invokerFieldAccess.getExpression() instanceof ThisExpression) {
              SimpleName newSimpleName=(SimpleName)newFieldInstructions.get(i);
              FieldAccess newFieldAccess=(FieldAccess)newSimpleName.getParent();
              targetRewriter.replace(newFieldAccess.getExpression(),newMethodDeclaration.getAST().newThisExpression(),null);
            }
          }
        }
        i++;
      }
    }
  }
}

Fixed version (ground truth):
private void modifyTargetPublicFieldInstructions(MethodDeclaration newMethodDeclaration){
  ExpressionExtractor extractor=new ExpressionExtractor();
  List<Expression> sourceFieldInstructions=extractor.getVariableInstructions(sourceMethod.getBody());
  List<Expression> newFieldInstructions=extractor.getVariableInstructions(newMethodDeclaration.getBody());
  FieldDeclaration[] fields=targetTypeDeclaration.getFields();
  for (  FieldDeclaration field : fields) {
    List<VariableDeclarationFragment> fragments=field.fragments();
    for (    VariableDeclarationFragment fragment : fragments) {
      SimpleName fragmentName=fragment.getName();
      int i=0;
      for (      Expression expression : sourceFieldInstructions) {
        SimpleName simpleName=(SimpleName)expression;
        if (simpleName.getParent() instanceof QualifiedName && fragmentName.getIdentifier().equals(simpleName.getIdentifier())) {
          QualifiedName qualifiedName=(QualifiedName)simpleName.getParent();
          if ((qualifiedName.getQualifier().resolveTypeBinding().isEqualTo(targetTypeDeclaration.resolveBinding()) || targetTypeDeclaration.resolveBinding().isEqualTo(qualifiedName.getQualifier().resolveTypeBinding().getSuperclass())) && qualifiedName.getQualifier().getFullyQualifiedName().equals(targetClassVariableName)) {
            SimpleName newSimpleName=(SimpleName)newFieldInstructions.get(i);
            targetRewriter.replace(newSimpleName.getParent(),simpleName,null);
          }
        }
 else         if (simpleName.getParent() instanceof FieldAccess && fragmentName.getIdentifier().equals(simpleName.getIdentifier())) {
          FieldAccess fieldAccess=(FieldAccess)simpleName.getParent();
          Expression fieldAccessExpression=fieldAccess.getExpression();
          if (fieldAccessExpression instanceof FieldAccess) {
            FieldAccess invokerFieldAccess=(FieldAccess)fieldAccessExpression;
            if ((invokerFieldAccess.resolveTypeBinding().isEqualTo(targetTypeDeclaration.resolveBinding()) || targetTypeDeclaration.resolveBinding().isEqualTo(invokerFieldAccess.resolveTypeBinding().getSuperclass())) && invokerFieldAccess.getName().getIdentifier().equals(targetClassVariableName) && invokerFieldAccess.getExpression() instanceof ThisExpression) {
              SimpleName newSimpleName=(SimpleName)newFieldInstructions.get(i);
              FieldAccess newFieldAccess=(FieldAccess)newSimpleName.getParent();
              targetRewriter.replace(newFieldAccess.getExpression(),newMethodDeclaration.getAST().newThisExpression(),null);
            }
          }
        }
        i++;
      }
    }
  }
  if (!targetTypeDeclaration.resolveBinding().getSuperclass().getQualifiedName().equals("String_Node_Str")) {
    IVariableBinding[] superclassFields=targetTypeDeclaration.resolveBinding().getSuperclass().getDeclaredFields();
    for (    IVariableBinding superclassField : superclassFields) {
      int i=0;
      for (      Expression expression : sourceFieldInstructions) {
        SimpleName simpleName=(SimpleName)expression;
        if (simpleName.getParent() instanceof QualifiedName && superclassField.isEqualTo(simpleName.resolveBinding())) {
          QualifiedName qualifiedName=(QualifiedName)simpleName.getParent();
          if (qualifiedName.getQualifier().resolveTypeBinding().isEqualTo(targetTypeDeclaration.resolveBinding().getSuperclass()) && qualifiedName.getQualifier().getFullyQualifiedName().equals(targetClassVariableName)) {
            SimpleName newSimpleName=(SimpleName)newFieldInstructions.get(i);
            targetRewriter.replace(newSimpleName.getParent(),simpleName,null);
          }
        }
 else         if (simpleName.getParent() instanceof FieldAccess && superclassField.isEqualTo(simpleName.resolveBinding())) {
          FieldAccess fieldAccess=(FieldAccess)simpleName.getParent();
          Expression fieldAccessExpression=fieldAccess.getExpression();
          if (fieldAccessExpression instanceof FieldAccess) {
            FieldAccess invokerFieldAccess=(FieldAccess)fieldAccessExpression;
            if (invokerFieldAccess.resolveTypeBinding().isEqualTo(targetTypeDeclaration.resolveBinding()) && invokerFieldAccess.getName().getIdentifier().equals(targetClassVariableName) && invokerFieldAccess.getExpression() instanceof ThisExpression) {
              SimpleName newSimpleName=(SimpleName)newFieldInstructions.get(i);
              FieldAccess newFieldAccess=(FieldAccess)newSimpleName.getParent();
              targetRewriter.replace(newFieldAccess.getExpression(),newMethodDeclaration.getAST().newThisExpression(),null);
            }
          }
        }
        i++;
      }
    }
  }
}