public Tag withKey(String key) {
        setKey(key);
        return this;
    }
<p>
A string that you can use to assign a value. The combination of tag keys and values can help you organize and
categorize your resources.
</p>

@param key
       A string that you can use to assign a value. The combination of tag keys and values can help you organize
       and categorize your resources.
@return Returns a reference to this object so that method calls can be chained together.
aws-java-sdk-applicationsignals/src/main/java/com/amazonaws/services/applicationsignals/model/Tag.java