public void setKey(String key) {
        this.key = key;
    }
<p>
A tag key, such as <code>Stage</code> or <code>Name</code>. A tag key cannot be empty. The key can be a maximum
of 127 characters, and can contain only Unicode letters, numbers, or separators, or the following special
characters: <code>+ - = . _ : /</code>
</p>

@param key
       A tag key, such as <code>Stage</code> or <code>Name</code>. A tag key cannot be empty. The key can be a
       maximum of 127 characters, and can contain only Unicode letters, numbers, or separators, or the following
       special characters: <code>+ - = . _ : /</code>
aws-java-sdk-opsworkscm/src/main/java/com/amazonaws/services/opsworkscm/model/Tag.java