public ComparatorCondition eq(S that) {
        return new ComparatorCondition("=", this, that);
    }
Returns a <a href=
"http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Expressions.SpecifyingConditions.html#ConditionExpressionReference.Comparators"
>comparator condition</a> (that evaluates to true if the value of the current
attribute is equal to that of the specified attribute) for building
condition expression.
aws-java-sdk-dynamodb/src/main/java/com/amazonaws/services/dynamodbv2/xspec/S.java