@Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        if (!super.equals(o)) {
            return false;
        }
        ExpressionOperator that = (ExpressionOperator) o;
        return op == that.op &&
               Objects.equals(children, that.children);
    }
@return True if it has at least one child that is enabled
stroom-query/stroom-query-api/src/main/java/stroom/query/api/ExpressionOperator.java