public String getSourceDBClusterIdentifier() {
        return this.sourceDBClusterIdentifier;
    }
<p>
The identifier of the Multi-AZ DB cluster that will act as the source for the read replica. Each DB cluster can
have up to 15 read replicas.
</p>
<p>
Constraints:
</p>
<ul>
<li>
<p>
Must be the identifier of an existing Multi-AZ DB cluster.
</p>
</li>
<li>
<p>
Can't be specified if the <code>SourceDBInstanceIdentifier</code> parameter is also specified.
</p>
</li>
<li>
<p>
The specified DB cluster must have automatic backups enabled, that is, its backup retention period must be
greater than 0.
</p>
</li>
<li>
<p>
The source DB cluster must be in the same Amazon Web Services Region as the read replica. Cross-Region
replication isn't supported.
</p>
</li>
</ul>

@return The identifier of the Multi-AZ DB cluster that will act as the source for the read replica. Each DB
        cluster can have up to 15 read replicas.</p>
        <p>
        Constraints:
        </p>
        <ul>
        <li>
        <p>
        Must be the identifier of an existing Multi-AZ DB cluster.
        </p>
        </li>
        <li>
        <p>
        Can't be specified if the <code>SourceDBInstanceIdentifier</code> parameter is also specified.
        </p>
        </li>
        <li>
        <p>
        The specified DB cluster must have automatic backups enabled, that is, its backup retention period must
        be greater than 0.
        </p>
        </li>
        <li>
        <p>
        The source DB cluster must be in the same Amazon Web Services Region as the read replica. Cross-Region
        replication isn't supported.
        </p>
        </li>
aws-java-sdk-rds/src/main/java/com/amazonaws/services/rds/model/CreateDBInstanceReadReplicaRequest.java