public S3DataAccessAsset withKeys(String... keys) {
        if (this.keys == null) {
            setKeys(new java.util.ArrayList<String>(keys.length));
        }
        for (String ele : keys) {
            this.keys.add(ele);
        }
        return this;
    }
<p>
S3 keys made available using this asset.
</p>
<p>
<b>NOTE:</b> This method appends the values to the existing list (if any). Use
{@link #setKeys(java.util.Collection)} or {@link #withKeys(java.util.Collection)} if you want to override the
existing values.
</p>

@param keys
       S3 keys made available using this asset.
@return Returns a reference to this object so that method calls can be chained together.
aws-java-sdk-dataexchange/src/main/java/com/amazonaws/services/dataexchange/model/S3DataAccessAsset.java