public DBInstance withMasterUsername(String masterUsername) {
        setMasterUsername(masterUsername);
        return this;
    }
<p>
The master username for the DB instance.
</p>

@param masterUsername
       The master username for the DB instance.
@return Returns a reference to this object so that method calls can be chained together.
aws-java-sdk-rds/src/main/java/com/amazonaws/services/rds/model/DBInstance.java