public DeleteItemSpec withValueMap(Map<String, Object> valueMap) {
        if (valueMap == null) {
            this.valueMap = null;
        } else {
            this.valueMap = Collections.unmodifiableMap(
                new LinkedHashMap<String, Object>(valueMap));
        }
        return this;
    }
Applicable only when an expression has been specified. Used to
specify the actual values for the attribute-value placeholders.
aws-java-sdk-dynamodb/src/main/java/com/amazonaws/services/dynamodbv2/document/spec/DeleteItemSpec.java