public BatchGetItemRequest addRequestItemsEntry(String key, KeysAndAttributes value) {
        if (null == this.requestItems) {
            this.requestItems = new java.util.HashMap<String, KeysAndAttributes>();
        }
        if (this.requestItems.containsKey(key))
            throw new IllegalArgumentException("Duplicated keys (" + key.toString() + ") are provided.");
        this.requestItems.put(key, value);
        return this;
    }
Add a single RequestItems entry

@see BatchGetItemRequest#withRequestItems
@returns a reference to this object so that method calls can be chained together.
aws-java-sdk-dynamodb/src/main/java/com/amazonaws/services/dynamodbv2/model/BatchGetItemRequest.java