Program: 12220
Project: 12220
Buggy source:
private void addDelegationInSourceMethod(){
  List<SingleVariableDeclaration> sourceMethodParameters=sourceMethod.parameters();
  String targetClassVariableName=null;
  for (  SingleVariableDeclaration parameter : sourceMethodParameters) {
    ITypeBinding parameterTypeBinding=parameter.getType().resolveBinding();
    if (parameterTypeBinding.isEqualTo(targetTypeDeclaration.resolveBinding())) {
      targetClassVariableName=parameter.getName().getIdentifier();
      break;
    }
  }
  FieldDeclaration[] fieldDeclarations=sourceTypeDeclaration.getFields();
  if (targetClassVariableName == null) {
    for (    FieldDeclaration fieldDeclaration : fieldDeclarations) {
      List<VariableDeclarationFragment> fragments=fieldDeclaration.fragments();
      for (      VariableDeclarationFragment fragment : fragments) {
        if (fieldDeclaration.getType().resolveBinding().isEqualTo(targetTypeDeclaration.resolveBinding())) {
          targetClassVariableName=fragment.getName().getIdentifier();
          break;
        }
      }
    }
  }
  if (targetClassVariableName == null) {
    for (    FieldDeclaration fieldDeclaration : fieldDeclarations) {
      List<VariableDeclarationFragment> fragments=fieldDeclaration.fragments();
      for (      VariableDeclarationFragment fragment : fragments) {
        if (targetTypeDeclaration.resolveBinding().isEqualTo(fieldDeclaration.getType().resolveBinding().getSuperclass())) {
          targetClassVariableName=fragment.getName().getIdentifier();
          break;
        }
      }
    }
  }
  ListRewrite methodBodyRewrite=sourceRewriter.getListRewrite(sourceMethod.getBody(),Block.STATEMENTS_PROPERTY);
  List<Statement> sourceMethodStatements=sourceMethod.getBody().statements();
  for (  Statement statement : sourceMethodStatements) {
    methodBodyRewrite.remove(statement,null);
  }
  Type sourceMethodReturnType=sourceMethod.getReturnType2();
  ITypeBinding sourceMethodReturnTypeBinding=sourceMethodReturnType.resolveBinding();
  AST ast=sourceMethod.getBody().getAST();
  MethodInvocation delegation=ast.newMethodInvocation();
  sourceRewriter.set(delegation,MethodInvocation.NAME_PROPERTY,ast.newSimpleName(movedMethodName),null);
  SimpleName expressionName=ast.newSimpleName(targetClassVariableName);
  sourceRewriter.set(delegation,MethodInvocation.EXPRESSION_PROPERTY,expressionName,null);
  ListRewrite argumentRewrite=sourceRewriter.getListRewrite(delegation,MethodInvocation.ARGUMENTS_PROPERTY);
  for (  SingleVariableDeclaration parameter : sourceMethodParameters) {
    if (!targetClassVariableName.equals(parameter.getName().getIdentifier())) {
      SimpleName argumentName=ast.newSimpleName(parameter.getName().getIdentifier());
      argumentRewrite.insertLast(argumentName,null);
    }
  }
  for (  String argument : additionalArgumentsAddedToMovedMethod) {
    if (argument.equals("String_Node_Str"))     argumentRewrite.insertLast(ast.newThisExpression(),null);
 else     argumentRewrite.insertLast(ast.newSimpleName(argument),null);
  }
  if (sourceMethodReturnTypeBinding.getName().equals("String_Node_Str")) {
    ExpressionStatement expressionStatement=ast.newExpressionStatement(delegation);
    methodBodyRewrite.insertLast(expressionStatement,null);
  }
 else {
    ReturnStatement returnStatement=ast.newReturnStatement();
    sourceRewriter.set(returnStatement,ReturnStatement.EXPRESSION_PROPERTY,delegation,null);
    methodBodyRewrite.insertLast(returnStatement,null);
  }
}

Fixed version (ground truth):
private void addDelegationInSourceMethod(){
  List<SingleVariableDeclaration> sourceMethodParameters=sourceMethod.parameters();
  String targetClassVariableName=null;
  for (  SingleVariableDeclaration parameter : sourceMethodParameters) {
    ITypeBinding parameterTypeBinding=parameter.getType().resolveBinding();
    if (parameterTypeBinding.isEqualTo(targetTypeDeclaration.resolveBinding()) && parameter.getName().getIdentifier().equals(this.targetClassVariableName)) {
      targetClassVariableName=parameter.getName().getIdentifier();
      break;
    }
  }
  FieldDeclaration[] fieldDeclarations=sourceTypeDeclaration.getFields();
  if (targetClassVariableName == null) {
    for (    FieldDeclaration fieldDeclaration : fieldDeclarations) {
      List<VariableDeclarationFragment> fragments=fieldDeclaration.fragments();
      for (      VariableDeclarationFragment fragment : fragments) {
        if (fieldDeclaration.getType().resolveBinding().isEqualTo(targetTypeDeclaration.resolveBinding()) && fragment.getName().getIdentifier().equals(this.targetClassVariableName)) {
          targetClassVariableName=fragment.getName().getIdentifier();
          break;
        }
      }
    }
  }
  if (targetClassVariableName == null) {
    for (    FieldDeclaration fieldDeclaration : fieldDeclarations) {
      List<VariableDeclarationFragment> fragments=fieldDeclaration.fragments();
      for (      VariableDeclarationFragment fragment : fragments) {
        if (targetTypeDeclaration.resolveBinding().isEqualTo(fieldDeclaration.getType().resolveBinding().getSuperclass()) && fragment.getName().getIdentifier().equals(this.targetClassVariableName)) {
          targetClassVariableName=fragment.getName().getIdentifier();
          break;
        }
      }
    }
  }
  ListRewrite methodBodyRewrite=sourceRewriter.getListRewrite(sourceMethod.getBody(),Block.STATEMENTS_PROPERTY);
  List<Statement> sourceMethodStatements=sourceMethod.getBody().statements();
  for (  Statement statement : sourceMethodStatements) {
    methodBodyRewrite.remove(statement,null);
  }
  Type sourceMethodReturnType=sourceMethod.getReturnType2();
  ITypeBinding sourceMethodReturnTypeBinding=sourceMethodReturnType.resolveBinding();
  AST ast=sourceMethod.getBody().getAST();
  MethodInvocation delegation=ast.newMethodInvocation();
  sourceRewriter.set(delegation,MethodInvocation.NAME_PROPERTY,ast.newSimpleName(movedMethodName),null);
  SimpleName expressionName=ast.newSimpleName(targetClassVariableName);
  sourceRewriter.set(delegation,MethodInvocation.EXPRESSION_PROPERTY,expressionName,null);
  ListRewrite argumentRewrite=sourceRewriter.getListRewrite(delegation,MethodInvocation.ARGUMENTS_PROPERTY);
  for (  SingleVariableDeclaration parameter : sourceMethodParameters) {
    if (!targetClassVariableName.equals(parameter.getName().getIdentifier())) {
      SimpleName argumentName=ast.newSimpleName(parameter.getName().getIdentifier());
      argumentRewrite.insertLast(argumentName,null);
    }
  }
  for (  String argument : additionalArgumentsAddedToMovedMethod) {
    if (argument.equals("String_Node_Str"))     argumentRewrite.insertLast(ast.newThisExpression(),null);
 else     argumentRewrite.insertLast(ast.newSimpleName(argument),null);
  }
  if (sourceMethodReturnTypeBinding.getName().equals("String_Node_Str")) {
    ExpressionStatement expressionStatement=ast.newExpressionStatement(delegation);
    methodBodyRewrite.insertLast(expressionStatement,null);
  }
 else {
    ReturnStatement returnStatement=ast.newReturnStatement();
    sourceRewriter.set(returnStatement,ReturnStatement.EXPRESSION_PROPERTY,delegation,null);
    methodBodyRewrite.insertLast(returnStatement,null);
  }
}