public Tag withKey(String key) {
        setKey(key);
        return this;
    }
<p>
The key of the tag.
</p>
<p>
Constraints: Tag keys are case-sensitive and accept a maximum of 127 Unicode characters. May not begin with
<code>aws:</code>.
</p>

@param key
       The key of the tag.</p>
       <p>
       Constraints: Tag keys are case-sensitive and accept a maximum of 127 Unicode characters. May not begin
       with <code>aws:</code>.
@return Returns a reference to this object so that method calls can be chained together.
aws-java-sdk-ec2/src/main/java/com/amazonaws/services/ec2/model/Tag.java