org.eclipse.core.runtime.AssertionFailedException: утверждение не выполнено:

Я пытаюсь создать таблицу со столбцом ComboBoxCellEditor. Когда я устанавливаю значение, приближается время ниже исключения.

import org.eclipse.jface.util.Policy;
import org.eclipse.jface.viewers.*;
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;

/............/

class TestBean {частное имя строки; личный ноутбук String; public String [] getListOfLaptop = {"Acer", "HP", "Lenovo", "Dell", "Benq"}; // методы получения и установки}

/............./

/..................../

class TestEditingSuport extends EditingSupport {
private int m_column;
private CellEditor m_editor;
public TestEditingSuport(ColumnViewer viewer, int column, 
String[] listOfTestBean) {
super(viewer);
m_column = column;
// Create the correct editor based on the column index
switch (column) {
case 0:
case 1:
m_editor = new ComboBoxCellEditor(
((TableViewer) viewer).getTable(), listOfTestBean);
break;
default:
}
}
@Override
protected CellEditor getCellEditor(Object element) {
    return m_editor;
}
@Override
protected boolean canEdit(Object element) {
    return true;
}
@Override
protected Object getValue(Object element) {
    TestBean bean = (TestBean) element;
    Object value = null;
    switch (m_column) {
    case 0:
        value = bean.getName();
        break;
    case 1:
        value = bean.getLaptop();
        break;
    default:
}
return value;
}
@Override
protected void setValue(Object element, Object value) {
TestBean bean = (TestBean) element;
switch (m_column) {
case 0:
if (valueChanged(bean.getName(), (String) value)) {
bean.setName((String) value);
}
getViewer().update(bean, null);
break;
case 1:
int index = (Integer) value;
String laptop = bean.getListOfLaptop[index];
if (valueChanged(bean.getLaptop(), laptop)) {
bean.setLaptop(laptop);
}
getViewer().update(bean, null);
break;
default:
}
}
private boolean valueChanged(String previousValue, String currentValue) {
boolean changed = false;
if ((previousValue == null) && (currentValue != null)) {
changed = true;
} else if ((previousValue != null) && (currentValue != null) && (!previousValue.equals(currentValue))) {
changed = true;
}
return changed;
}
}

/............../

class TestContentProvider implements IStructuredContentProvider {
@Override
public Object[] getElements(Object inputElement) {
return (Object[]) inputElement;
}
}

/........................./

class TestColumnLabelProvider extends ColumnLabelProvider {
private int m_column;
public TestColumnLabelProvider(int column) {
this.m_column = column;
}
public String getText(Object element) {
String text = null;
if (element instanceof TestBean) {
TestBean testBean = (TestBean) element;
switch (m_column) {
case 0:
text = testBean.getName();
break;
case 1:
text = testBean.getLaptop();
break;
default:
}
}
return text;
}
}

/....................../

import org.eclipse.jface.util.Policy;
import org.eclipse.jface.viewers.*;
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;