public void setFilter(String filter) {
        this.filter = filter;
    }
<p>
An expression that looks like a SQL WHERE clause that must return a Boolean value. Messages that satisfy the
condition are passed to the next activity.
</p>

@param filter
       An expression that looks like a SQL WHERE clause that must return a Boolean value. Messages that satisfy
       the condition are passed to the next activity.
aws-java-sdk-iotanalytics/src/main/java/com/amazonaws/services/iotanalytics/model/FilterActivity.java