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