public void setKey(String key) {
        this.key = key;
    }
<p>
The key for the tag. Tag keys are case sensitive. Every DAX cluster can only have one tag with the same key. If
you try to add an existing tag (same key), the existing tag value will be updated to the new value.
</p>

@param key
       The key for the tag. Tag keys are case sensitive. Every DAX cluster can only have one tag with the same
       key. If you try to add an existing tag (same key), the existing tag value will be updated to the new
       value.
aws-java-sdk-dax/src/main/java/com/amazonaws/services/dax/model/Tag.java