@Override
    public Expression[] getBaseAggregators() {
        Expression maxAggregator = Expression.function("max",
                Expression.variable(getBaseAttributes()[0].getName()));
        return new Expression[]{maxAggregator};
    }
{@link IncrementalAttributeAggregator} to calculate maximum value based on an event attribute.
modules/siddhi-core/src/main/java/io/siddhi/core/query/selector/attribute/aggregator/incremental/MaxIncrementalAttributeAggregator.java