ph-schematron/src/main/java/com/helger/schematron/pure/binding/xpath/PSXPathVariables.java
@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);
  }
@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);
  }
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>.