Erro ao criar e arrasta JavaBeans

package componentes;  
  
import java.beans.*;  
import java.io.Serializable;  
import javax.swing.JTextField;  
import javax.swing.SwingConstants;  
  
/** 
* 
* @author Administrador 
*/  
public class MeuTextField extends JTextField implements Serializable {  
      
    public static final String PROP_SAMPLE_PROPERTY = "sampleProperty";  
    private String sampleProperty;  
    private PropertyChangeSupport propertySupport;  
      
    public MeuTextField() {  
        propertySupport = new PropertyChangeSupport(this);  
    }  
      
    public String getSampleProperty() {  
        return sampleProperty;  
    }  
      
    public void setSampleProperty(String value) {  
        String oldValue = sampleProperty;  
        sampleProperty = value;  
        propertySupport.firePropertyChange(PROP_SAMPLE_PROPERTY, oldValue, sampleProperty);  
    }  
      
    @Override  
    public void addPropertyChangeListener(PropertyChangeListener listener) {  
        propertySupport.addPropertyChangeListener(listener);  
    }  
      
    @Override  
    public void removePropertyChangeListener(PropertyChangeListener listener) {  
        propertySupport.removePropertyChangeListener(listener);  
    }  
}