public void setKey(String key) {
        this.key = key;
    }
<p>
A key is the required name of the tag. The string value can be 1-128 Unicode characters in length and can't be
prefixed with "aws:" or "dms:". The string can only contain only the set of Unicode letters, digits, white-space,
'_', '.', '/', '=', '+', '-' (Java regular expressions: "^([\\p{L}\\p{Z}\\p{N}_.:/=+\\-]*)$").
</p>

@param key
       A key is the required name of the tag. The string value can be 1-128 Unicode characters in length and
       can't be prefixed with "aws:" or "dms:". The string can only contain only the set of Unicode letters,
       digits, white-space, '_', '.', '/', '=', '+', '-' (Java regular expressions:
       "^([\\p{L}\\p{Z}\\p{N}_.:/=+\\-]*)$").
aws-java-sdk-dms/src/main/java/com/amazonaws/services/databasemigrationservice/model/Tag.java