public String getKey() {
        return this.key;
    }
<p>
The key for the filter.
</p>
<p>
Run the <a>DescribePatchProperties</a> command to view lists of valid keys for each operating system type.
</p>

@return The key for the filter.</p>
        <p>
        Run the <a>DescribePatchProperties</a> command to view lists of valid keys for each operating system
        type.
@see PatchFilterKey
aws-java-sdk-ssm/src/main/java/com/amazonaws/services/simplesystemsmanagement/model/PatchFilter.java