code: @Nonnull
    public EChange removeAll (@Nullable final Iterable <String> aVars)
    {
      EChange eChange = EChange.UNCHANGED;
      if (aVars != null)
        for (final String sName : aVars)
          eChange = eChange.or (remove (sName));
      return eChange;
    }
  
    @Nonnull
    @ReturnsMutableCopy
    public ICommonsNavigableMap <String, String> getAll ()
    {
      return m_aMap.getClone ();
    }
  
    public boolean contains (@Nullable final String sName)
    {
      if (StringHelper.hasNoText (sName))
        return false;
      return m_aMap.containsKey (sName);
    }
docs: Remove all variables with the specified names
  
  @param aVars
  A list of variable names to be removed. May be <code>null</code>.
  @return {@link EChange#CHANGED} if at least one variable was removed
  successfully. Never <code>null</code>.