Eclipse Exceptional Parsing Throws False Positive NullPointerException

I am experimenting with Messages classes instead of using hard-coded strings for custom displays. However, I am getting a warning Potential null pointer access: this expression has a '@Nullable' type

from Eclipse (Luna - 4.4.1) with the following code:

In package-info.java:

/**
 * My pacakge of tests.
 *
 * @author Flic
 */
@NonNullByDefault
package org.sample;

import org.eclipse.jdt.annotation.NonNullByDefault;

      

        
        
        
      

    

In Messages.java:

package org.sample;

import static java.util.ResourceBundle.getBundle;

import java.util.*;
import org.eclipse.jdt.annotation.Nullable;

public class Messages
{
  private static final String BUNDLE_NAME = "org.sample.messages"; //$NON-NLS-1$
  private static final @Nullable ResourceBundle RESOURCE_BUNDLE = 
                                                 getBundle(BUNDLE_NAME);

  private Messages()
  {
  }

  public static @Nullable String getString(String key)
  {
    String msgVal = null;
    try
    {
      if (RESOURCE_BUNDLE != null)
        msgVal = RESOURCE_BUNDLE.getString(key);  // Warning on RESOURCE_BUNDLE
    }
    catch (MissingResourceException mrEx)
    {
      msgVal = '!' + key + '!';
    }

    return msgVal;
  }
}

      

        
        
        
      

    

The warning goes away if I copy the member variable to local and check instead:

public static @Nullable String getString(String key)
{
  ResourceBundle checkBundle = RESOURCE_BUNDLE;
  String msgVal = null;

  try
  {
    if (checkBundle != null)
      msgVal = checkBundle.getString(key);  // No warning here
  }
  catch (MissingResourceException mrEx)
  {
    msgVal = '!' + key + '!';
  }

  return msgVal;
}

      

        
        
        
      

    

Can anyone explain why null checking a static final member variable is not enough to avoid a potential null pointer, but assigning its value to a local variable and checking that it is ok instead? Similar checks with String or Integer member variables are apparently specific to ResourceBundle objects.