public FilterValidator isBinary(final BinaryOperatorKind binaryOperator) {
    if (!(curExpression instanceof Binary)) {
      fail("Current expression is not a binary operator");
    }

    Binary binary = (Binary) curExpression;
    assertEquals(binaryOperator, binary.getOperator());
    return this;
  }
 public FilterValidator isBinary(final BinaryOperatorKind binaryOperator) {
   assertTrue("Current expression not a binary operator", curExpression instanceof Binary);
   Binary binary = (Binary) curExpression;
   assertEquals(binaryOperator, binary.getOperator());
   return this;
 }