public DeleteItemSpec withNameMap(Map<String, String> nameMap) {
        if (nameMap == null) {
            this.nameMap = null;
        } else {
            this.nameMap = Collections.unmodifiableMap(
                new LinkedHashMap<String, String>(nameMap));
        }
        return this;
    }
Applicable only when an expression has been specified.
Used to specify the actual values for the attribute-name placeholders,
where the value in the map can either be string for simple attribute
name, or a JSON path expression.
aws-java-sdk-dynamodb/src/main/java/com/amazonaws/services/dynamodbv2/document/spec/DeleteItemSpec.java