Program: 71215
Project: 71215
Buggy source:
public static Optional<Pair<String,String>> create(StringProperty property){
  Dialog<Pair<String,String>> dialog=new Dialog<>();
  dialog.setTitle("String_Node_Str");
  dialog.setHeaderText("String_Node_Str");
  ButtonType loginButtonType=new ButtonType("String_Node_Str",ButtonBar.ButtonData.OK_DONE);
  dialog.getDialogPane().getButtonTypes().addAll(loginButtonType,ButtonType.CANCEL);
  GridPane grid=new GridPane();
  grid.setHgap(10);
  grid.setVgap(10);
  grid.setPadding(new Insets(20,150,10,10));
  TextField propertyName=new TextField();
  propertyName.setPromptText("String_Node_Str");
  propertyName.setText(property.getName());
  TextField propertyValue=new TextField();
  propertyValue.setPromptText("String_Node_Str");
  propertyValue.setText(property.getValue());
  grid.add(new Label("String_Node_Str"),0,0);
  grid.add(propertyName,1,0);
  grid.add(new Label("String_Node_Str"),0,1);
  grid.add(propertyValue,1,1);
  Node loginButton=dialog.getDialogPane().lookupButton(loginButtonType);
  propertyName.textProperty().addListener((observable,oldValue,newValue) -> {
    if (newValue.equals(property.getName())) {
      loginButton.setDisable(false);
    }
 else {
      loginButton.setDisable(property.getParent().getChildren().containsKey(newValue));
    }
  }
);
  dialog.getDialogPane().setContent(grid);
  Platform.runLater(() -> propertyName.requestFocus());
  dialog.setResultConverter(dialogButton -> {
    if (dialogButton == loginButtonType) {
      return new Pair<>(propertyName.getText(),propertyValue.getText());
    }
    return null;
  }
);
  Optional<Pair<String,String>> result=dialog.showAndWait();
  return result;
}

Fixed version (ground truth):
public static Optional<Pair<String,String>> create(StringProperty property){
  Dialog<Pair<String,String>> dialog=new Dialog<>();
  dialog.setTitle("String_Node_Str");
  dialog.setHeaderText("String_Node_Str");
  ButtonType loginButtonType=new ButtonType("String_Node_Str",ButtonBar.ButtonData.OK_DONE);
  dialog.getDialogPane().getButtonTypes().addAll(loginButtonType,ButtonType.CANCEL);
  GridPane grid=new GridPane();
  grid.setHgap(10);
  grid.setVgap(10);
  grid.setPadding(new Insets(20,150,10,10));
  TextField propertyName=new TextField();
  propertyName.setPromptText("String_Node_Str");
  propertyName.setText(property.getName());
  TextField propertyValue=new TextField();
  propertyValue.setPromptText("String_Node_Str");
  propertyValue.setText(property.getValue());
  grid.add(new Label("String_Node_Str"),0,0);
  grid.add(propertyName,1,0);
  grid.add(new Label("String_Node_Str"),0,1);
  grid.add(propertyValue,1,1);
  Node loginButton=dialog.getDialogPane().lookupButton(loginButtonType);
  propertyName.textProperty().addListener((observable,oldValue,newValue) -> {
    if (newValue.equals(property.getName())) {
      loginButton.setDisable(false);
    }
 else {
      loginButton.setDisable(property.getParent().getChildren().containsKey(newValue));
    }
  }
);
  dialog.getDialogPane().setContent(grid);
  Platform.runLater(propertyName::requestFocus);
  dialog.setResultConverter(dialogButton -> {
    if (dialogButton == loginButtonType) {
      return new Pair<>(propertyName.getText(),propertyValue.getText());
    }
    return null;
  }
);
  return dialog.showAndWait();
}