public Boolean execute(ComplexEvent event) {
        Object left = leftExpressionExecutor.execute(event);
        Object right = rightExpressionExecutor.execute(event);
        return !(left == null || right == null) && execute(left, right);
    }
Parent Executor class for Compare conditions. common evaluation logic is implemented within executor.
modules/siddhi-core/src/main/java/io/siddhi/core/executor/condition/compare/CompareConditionExpressionExecutor.java