public static ExpressionOperator combine(final ExpressionOperator in,
                                             final ExpressionOperator decoration) {
        if (in == null) {
            return decoration;
        } else if (decoration == null) {
            return in;
        }

        return ExpressionOperator
                .builder()
                .addOperator(in)
                .addOperator(decoration)
                .build();
    }
Simplify an expression to improve comprehension and make processing faster.

@param item The expression to simplify.
@return The simplified expression.
stroom-query/stroom-query-api/src/main/java/stroom/query/api/ExpressionUtil.java